Zebbi,
The differences you see are because the plugins use different calculations to determine y position when jumping.
The standard plugin (and Platform Plus) both incorrectly approximate the new y position as if the velocity over the previous tick was constant - they assume that y distance traveled is equal to velocity multiplied by time; the error here is that velocity is not constant because of acceleration due to gravity. Newton's equations account for this and Platform2 uses one of them to correctly set the new y position. By not using the correct equations of motion, the standard plugin suffers from inconsistent jump behavior when delta-time varies (jump heights change if delta-time changes).
Unfortunately that means that it is not possible for the Platform2 jumps to ever be the same as the standard plugin's - you can tweak jump velocity and gravity so that the jump height or jump time are similar, but you can't have them all the same - you are asking if there's a way to make the Platform2 jumps behave like the standard plugin's (non-quadratic movement) when really you should be asking scirra to fix the standard plugin so it uses correct calculations to determine jump position...
Thanks for the explanation, it's been driving me nuts trying to figure out where I was going wrong! Indeed both built-in and plus are nerve-wracking, I can barely ever match anything due the inconsistencies of the jump heights, fall speeds, etc. I used to do a similar thing with matching the awful built-in Clickteam platform movement to their far superior platform extension, and even though the built-in didn't have proper push-out (you could see in debug the character going into the ground, then placed on the floor surface!) the movements still matched, so I can't imagine why Scirra left it like this.
As a compromise, I'll probably leave it with a matched jump height and fall time, that was at least nothing in the game will be compromised in terms of jump distances.
Colludium Here's a wall-jump capx that uses Platform+ and Platform2: dropbox.com/s/6bn837q29lklnzj/walljumpplatformplus.capx - I've tried to match the walljump from Platform+ as best as I can, but with the difference in gravity, the only similarities I can match almost perfectly is the jump out distance and the point in which they return to the wall. Hopefully, someone better skilled can look at these events and improve them, as they might serve as a solid basis for any Platform2 games that require wall jump. If something like this was built into Platform2 it would be a lifesaver, is there any consideration for adding a wall-jump like this to the engine? I'm sure with code it could be a lot more reliable, certainly than my own events ;)