I have an Elite 510 and I'm waffling on the issue of an ISF. When I first got my set it had a problem and my dealer sent out his ISF Certified tech who fixed it. He told me the focus(electronic and mechanical focus I believe is what he said)looked very good and he didn't believe it could be improved. He also attached a device to the set and measured the color temp at 7200k in the B&W mode. The other modes were much higher so he suggested I stick to the B&W which I did. He also tweeked the set with the Avia disc. To be honest the unit looks so good with dvd and hdtv I'm having a hard time convincing myself an ISF will make a material improvement. Are there other Elite 510,610 or 710 owners out there who have taken the plunge? Are you happy with the improvement? Knowing what you know now would you do it again? The gentleman who worked on my set told me the Elites are usually better factory calibrated than most other RPTV and as result I'm afraid to risk the $6-700.