As far as ohms go, I think its more about getting wattage out the amp as well as versatility. If you have a 8ohm cab, there are some amps that only run at 4 or 2, so you would have to get Another 8 ohm cab to pair in order to run your head. Also, like my GBE 600, its like 175 watts(somethin like that) at 8ohms, but 475watts at 4 ohms. So if you want more than 175 watts, you got a little more to think about. 8 or 4 or 2 ohm cabs arent good or bad, its just the preference. I have a 4ohm cab cause I dont plan on adding to it, where as I know ppl that want 8ohm cabs because they want to pair them with other cabs to push more air.
Trace Elliott is a very reliable company. They were the joints back in the day. Ive used their amps quite a few times. Only thing is most of their gear is like the old school weighty ones. I dont think they have designed anything to keep up with the lightweight craze so thats something to consider. Nevertheless, you cant go wrong with TE.