To be honest, I've not noticed anything yet. I'd have to watch traffic, though, to be sure. My computer's the wired one.I've seen some stray folks complain about drop outs on the 4500. Have you seen anything like that yet yourself?
The only possible drop might have been when we were initially setting up the TiVO. At one point, there did seem to be a drop. However, part of the issue may have been the positioning of the adaptor. Apparently TiVOs are picky about their adaptors, and you're pretty much stuck with the TiVO adaptor, even though it's a wireless G, since the TiVO ones are the only ones known to work consistently with TiVO. At any rate, we had an initial drop, but since then the connection seems to be okay.
I'm not sure if there are drops with my husband's computer. Since we recently moved, it's not as if he's had a lot of time to use it. I think the real test will be when we get him a new notebook. He loves the mobility of the notebook computer, so he'll use it in different parts of the house. If he has drops at that point, he'll certainly say something about it!