If you're ok with the added thickness just get the Skyrocket, then you get a slightly bigger battery, LTE (where available), bigger screen, etc.
I considered the SkyRocket... It is a poor option. Faster CPU, bigger screen, LTE that can not be turned off. Review I read said LTE by itself is a big power drain and is somewhat useless with no unlimited data plans from AT&T. The 200mAh is not going to be enough to cover the added power drain. Then you have problems with ROM and case compatibility, faster CPU does nothing practical, fatter phone, etc.
AT&T had the best design for the SGSII, but they had to go and botch it up by minor tweaks that screw up full compatibility.
I am okay with flipping phones on eBay, but I would rather have the SGSII international or a 2000mAh battery that works without modding.