For me, and from what i understand, being able to have an option to chose between 30 or 60 fps would be a good feature, in order to match more easaly older devices.
You can do that in Stencyl for exemple, with a lign of code.
For example, I have framerate drops on my ipod4 with my project (an universal apple app), as i said on another thread, from 60 to 55, and i can really notice them, even if my fps is high for such a device : i would prefer to have a stable and solid 30, and my framerate drops to not be noticable.
Idealy, being able to choose that framerate depending of the resolution of the device or whatever would be nice.
It would give us a good window of safety concerning this point on older devices, as we can still make the game running at full speed with dt.
But maybe it's difficult to implement, or would not look good, I don't know, or maybe i just understand badly how fps work, but in my mind, at the moment, it would be great !
Otherwise, auto resizing images concerning the resolution, as i suggested before, would be the very best option, to my opinion : it would make us reach 60 fps really more easaly on the older devices, as the images would be divided by 2 for example :)
Darklinki : timescale work on that devices for example, so maybe it's possible to implement it, even if it's different of course.