12-28-2012 01:55 PM
Believe me, if you want an 800 score, all else being equal, you want utilization under 10%. I'm not saying you can't get there with higher utilization than that, but I am saying that putting your utilization under 10% will always get you a score increase. 20% or 40% is a good start, but you HAVE to get lower to get the best impact.
I understand that the question involves other utilization theories, but all of that is going to speculation and subject to individual experiences. The 1% - 9% theory is not subject to individual experiences (except in extreme situations of 400 and 500 credit scores, where utilization is the least of your worries). So that's where my advice ends.
My present EQ FICO with a utilization of 10% is in the 800s. That's with a large balance on one card and a small on another. TU doesn't use the former for utilization, so you would expect a higher score because of it, but no. EX though is nicer.