Yeah, it would be more convenient if XMPlay looked for files with a ".png" extension in addition to ".bmp", and there isn't really any good reason not to, so here's an update that will do that...
Thanks Ian, 3.8.0.3 works fine with <png-file>.png!
Note that a skin using PNG files will be a bit slower loading than if it was using BMP files, as PNG requires extra processing/decompression. The difference probably won't be very significant/noticeable...
No, it is not significant/noticeable at all. Especially in regard to the advantage of having transparency support!
... still it's probably best to stick with BMP when possible, unless PNG significantly reduces the compiled skin's size (I've not done enough comparisons to say whether it does).
I don't think it makes any difference in file size (at least for ZIP-compiled skins).
A bmp will be zipped at the ZIP-compilation of the skin where a png is already ZIP-deflated.
Six of one, half a dozen of the other...