I think I am set on the JBL. I think JBL offers one of the best price/power combinations. Although there are certainly other amps out there, and other people on CEG will advocate for other brands, the JBL is my pick. If I could get a PPI Art Series 4-ch that was actually in good condition used, I might get one, unfortunately, the ones I've seen on eBay are usually pretty battered. In terms of other amps, you also might look at something with a little more power (I think JBL has another amp that offers more power w/4 channels) depending on your needs. I don't recall the specs on the Ultimate components you were looking at. Good luck with your install.
For other good amp brands, I believe there is a thread in this category regarding the best audio brands for each component of a complete audio system (i.e. sub, amp, components, etc). I think the title of the thread is "The Best of...(No Flames)". If you search for "no flames" you should find it. There are a lot of good amp recommendations there.
