presets vs. programming... it's tit for tat - and who wouldn't be happy with tit for tat? they both can be too time consuming and sound good or bad as well as fresh or stale. suppose the odds of sounding overused is greater for presets, but programming doesn't always sound original either. like Nick, i use the presets to ballpark, then adjust the settings till it sounds right. use the same approach for synths and fx.
as for writing, keep it very simple and record the midi using a piano patch or something that is somewhat like the sound you're after. then, after the song is written and a rough draft recorded, go in and find the proper sound. i do the same for guitar. record everything dry, then find the tone later... whether re-amping through a real amp, using a plugin (amplitube/ guitar rig), or a combination of things.
if you can't or don't wanna use midi. record first with a simple patch, then go back later, find the right sound and re-record with the preferred patch
record the ideas first, then worry about getting the right sound.
having templates is a great idea. the quicker you can go from having the idea to actually recording that idea, the better.... (usually)