I like the the riff idea very much, bit of a doomy feel to it.
I have a similar mic problem, it seems not to get the whole range, ive tried eqing but it still s@cks. Going to try a condensor usb mic, maybe its just the directness of the sound, so without the rebound from the walls, that throws me off track though......
My Toneport Plexi model also sounds like the Plastic model, its just like that i guess.....
EDIT: Thinking about this maybe a combination of room micing and direct micing will do the trick, owell anyway, still need a condensor mic then.....