My opinion about this as a mapmaker is that you should try to release it for both if it can be done. However, myself I will never release anything for inifinity again because I need the higher polygon limits when I mapmake. I would also like to see the pfhortran script code to be less buggy. It's very cool but sad we mapmakers can't use it as it won't work from a saved gamefile.
Here's my sum up about the engines...
alephone
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-higher polygon limits
-scripting (sometimes buggy, don't know if this is fixed)
-high res textures (transparent masks, those are cool)
-higher resolutions
-recorded movies can only be replayed on your own computer
-crashes??? (I have never experienced this)
-background music to your levels through scripting
-crosschairs
-better controls
-runs on many systems (even windows)
Infinity
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-stable
-needs classic if you use intallers
*** If you decide to release for alephone make sure to include 128x128 textures for those with slower computers.