Personally IMO, I record my pads, patches, rhodes & strings in stereo. Then do my bass and some other sounds (depends on the patch) in mono. I like to capture the feel & nuance of certain sounds (ex. rhodes panning left/right) so it's a matter of choice when to use stereo or mono

keyboard patches are usually optimized for stereo so I always do that- sometimes mono sits better in the mix, though, but if you recorded in stereo you always have that option

Record it in midi. Then at mixdown you can make a better decision of stereo or mono, since you'll be hearing it in context with all the other elements. Then you also have the option to change which patch used.

Of course, that's only if you have the keyboard available at mixdown time.

Thanks for the tips, don't know why I never thought to play with it more while in midi :( Also any tips on creating the stereo impression with a mono track? I've done things like runnig a delay and panning it opposite the original signal. Are there any other standard or even not so standard methods?

Thanks