Physiologically, the data seems to support what you stated. However, I've done both options (arrive the day before and camp for a 4-5 days at 7,000 or 8,000 altitude) and I really prefer the 4-5 days option.
Here's why. Physically, I really haven't been able to tell the difference between the two. Probably because I'm not fast enough that it really matters :-) Psychologically, however, I feel MUCH better going out there early and spending some time hiking up around 11,000 feet for a few days. Doing so brings all the fun effects of altitude enough so that I remember what it feels like and am not surprised on race day when I feel like I'm going to die. I like having that mental reference for when things get hard. Just knowing that it really is normal is a comfort, if that makes sense.
Oh, that and the desire to "acclimate" makes for a compelling excuse to go enjoy the mountains and not be at work.