Some more or less useful thoughts on my end.

This is such a huge topic and when it comes down to the details, it is, as with most things, absolutely a matter of personal preferences.
I had a talk with Augustinas a while back where I also covered a bit about different drive systems in general. If anyone's curious there's a link below to the whole video.

In both cases, a huge impact besides the shape of the cam is also the leverage or the leverages. Mainly between the cam and the footboard (how far the footboard is sticking out in relation to the cam) but also from the center of the axis out to the pivot point of the direct drive or rolling surface of the strap.

When I started designing the first version of the Darwin, I had only a simple strap drive in mind. A bit later I had the idea of the split cam which additionally also allowed me to adapt a direct drive system.
In my eyes, the strap drive is the modern evolution of the chain drive which has its history of serving as an alternative for leather straps and other not-so-ideal materials back in the very old days.
With the modern materials we have now, it is possible to have a super durable but also smooth and lightweight drive setup and in my opinion no need for a greasy and clunky chain anymore

The thing with a rolling drive system is that the feeling during the whole beater motion stays either linear or with an increased progressiveness. - Some other things like a certain and abrupt drop or change within the geometry of the cam can also tweak the feeling in one way or another. Mainly it means that a strap drive feels more natural and in line with the regular motion of your foot or leg. Excentric cam layouts can additionally add more force to the stroke without actively demanding the same amount of force coming from the player since once the footboard/beater starts moving, it keeps moving and can act supportively to the additional power required to overcome the increased leverage during the movement.

If we ignore the increasing spring tension during the movement and only pay attention to the geometry on a strap drive.
Round cam: the footboard/stroke feels the same all the way through.
Excentric cam: the feeling starts to become a bit heavier to the decreasing leverage between the strap cam and footboard
Additional power edge: can be set if a very abrupt change from light to a heavier feel is wanted (the old Flexiglide Iron Cobra had a rather extreme setting - an eccentric cam that was one big power edge)

With direct drive, the whole story is a bit different. Personally speaking, it's not my favorite setup but it is absolutely astonishing to see what people are able to achieve with various setups and there's definitely nothing wrong with any setup.

It's super interesting that the ongoing hype about direct drive being the ultimate choice for fast and heavy stuff is still going strong, even after decades.
The thing is that a usual direct drive motion doesn't feel the same all the way through. - Depending on the angle set and once again with the increasing spring tension ignored the following starts to happen during the pedal's move:
It more or less starts a bit on the heavy side but becomes increasingly lighter towards the midway point and further and then starts to increasingly feel heavier again (depending on your angle set). So if anyone wondered or had the feeling that the pedal is "running away" under your feet, now you know. This is also the reason why usually less power gets transferred to the drumhead. If you look at a stock Axis direct drive configuration, the top pivot point of the direct drive is facing about 45° upwards and when the beater hits the head, it sits fairly horizontally behaving exactly the opposite way as a chain or strap drive pedal with an eccentric cam would do.

On the direct drive, besides the facing angle of the top pivot point in relation to the center of the cam, the most influence on the feeling has the leverage (if you tried an A series Axis pedal and played around with the lever adjustment on the top of the cam you know what I mean).
Interestingly the leverage between the top pivot point and the bottom pivot point of the direct drive link, especially in relation to the leverage mentioned above plays a huge role in the overall feeling.
The Darwin in its stock direct drive configuration has a rather conservative and almost chain-like feel - You can get also a lot of speed and power through it. Simply because direct drive link sits almost vertically (if you look at the pedal from the side) and the footboard portion is sticking out quite a bit further than usual. So the more in an angle you get the direct drive link, the more it will start to feel and behave like a direct drive pedal.

It is crazy how much you can twist the direct drive adjustments on the Darwin and further how crazy the feeling can change depending on how all the different parameters and leverages are set (it's always great to see the reaction when I have the opportunity to guide someone through all the possible settings and some sample combinations).
Usually, the limitations are mechanical since at one point the direct drive link would either interfere with the main axis, the cam itself, or the driveshaft. When I updated the design to the current FTW version, I mirrored the slave pedal (achieving a symmetrical setup) bringing the direct drive link to the other side and away from the driveshaft. This offers to realize all possible setup combinations without any mechanical interferences or limitations anywhere and is something unique and no other pedal can accomplish :-)

So to make this long story even longer, I hope that there's something helpful in there.
Whenever someone's uncertain and asks for advice, I recommend giving the strap drive a try. It usually offers more control and gives you the feeling that the pedal is really playing with you. You also might wonder how crazy fast and powerful this setup can be and there's absolutely no reason to hide it behind a direct drive setup.
Some long-term direct drive fans were a bit skeptical at first but also curious and switched to the strap drive setup completely after having the pedal converted for a while.

All the best
Dennis