I've played with the Gigrac 1000, Yamaha 512 and own a Yammie 5000/12.
The 5000/12 was purchased here for about $500 and I bought a case for another hun. Audio quality wise the Gigrac and 512 aren't in the same league and flexibility wise they aren't even close. They both have plenty of power for a small to medium club for mono mains and monitors. If I were choosing between those two I would have a hard time as the 512 can be had for peaniuuts used and I don't see used GigRac 1000's around that often. If I were buying new I think it would be the Gigrac based on sound quality.
If you can stand the extra size, weight and cost, a used 5000/12 is a big step up. Cost wise they are pretty depressed as there is a newer model (5012c) that has a one knob compressor on the first 6 channels.
My config:
JBL EON Powered tops
Lo Pass out to a QSC RMX 850, bridged for a single 1x12 based sub
Aux 1 drives monitors @500/4ohm
Aux 2 drives keys into @500/4 ohm.
alternatively I use Aux 1 & 2 as separate monitor mixes.
I also have a 4 space rack with a power filter, 4 compressors in 1 RU (old Apeh Easy Rider), an EQ and a separate compressor that functions as a brickwall limiter on the tops.
The external EQ does the monitors and I use the on board 9 band for mains. That single 9 band is probably the biggest limitation on the 5000/12. The 512 and Gig rac both have 2 9 band EQ's. They still don't sound great but they are functional.
As far as the outboard stuff I have goes - I have done a few gig's with just the board and 2 monitors - 1 as the foh, 1 aimed back - and no external stuff. That worked fine for a fairly low volume, largely acoustic instrument oriented thing.
