I understand what you say. Spending lots of effort matching your game so it works on JavaME. With what I try to do I hope I only need to go through this trouble once, and then be able to create simple (at least 2d) games to compile for all platforms. So far the trouble I encounter is for all mobile platforms, not just JavaME.

What sort of trouble did you run into specifically?

I have a Nokia running JavaME, and it starts to work; it compiles to,and runs on the device. True, didn't solve all problems yet. I hope performance will improve after making certain parts more efficient. But if other, more heavy apps can run well on it, should be possible for me as well. Currently trying to fake 3d (thus far Mosync only supports 2d for non-android and non-iOS platforms) with some extensive calculations. It draws the performance back too much.

The emulator is also a lot faster than my phone, so I regularly check on the real thing. Mosync uses bluetooth connection to compile towards the device, so I only need to hit "the other" compile button, and it uploads to my phone. Plans are at Mosync to include old mophun (former game sdk for JavaME and other platforms). Still a long shot though.