rg1570 compared to 1527?

[PiSan]

First I'd like to say this site has been a valuable resource and I've been lurking around it for a bit. I'd like to get a new guitar sometime soon and started looking at the Ibanez RG series.

For my price range the rg1570 fits right in for $640 + case at. However I have been briefly considering a seven string 1527 which is only $30 more. Are there notable differnces between the two that I should be wary of?

[Polaris20]

One extra string on the 1527, one extra pup on the 1570.

[PiSan]

If I could get a 7620, do you think it'd be a better purchase? It'd be used so I'd be saving money anyway.