The Blaze are an excellent choice, but I personally love the new D-Sonic (Drop-Sonic) pickup that also comes in a 7 string version, smack this in the bridge position and you'll have a pup that's hotter than any DiMarzio Evolution I've ever played, the low end is thick and tight, harmonics also jump out easily, it's a great.
John Petrucci from Dream Theater now uses them on his guitars, if you listen to the latest album, or anything from the last DVD, then you'll get a good idea of what it sounds like. I'd record something with it but unfortunately at the moment all I have is an amp modeller setup, which imo doesn't really demonstrate a pup fully.
EDIT: Why are you downgrading by the way? Do you prefer fixed bridges? I'd really try and find a 7321 in a shop if possible, as construction quality on the lower (Korean) made Ibanez guitars can vary (just like on any guitar, but it's best to be more careful with low budget ones imo), you'll definately be able to find one with decent fretwork, but the amount of lemons at that price range will be much more common than those in the Japanese built (like your 7620) price range.
