I bought regularly from them in the 80s with their 35- and 50-cent ads. I was able to accumulate a lot of cool comics, and nearly all were newsstand mint.
The last I bought from them may have been in the mid-00s, when I could go and order a ton of low-to-mid-grade romance comics for a song. Now that I am setting up at shows, however, I rarely buy anything online (except for here and eBay), and only rarely check his site. I most often look over there to see how he has priced some of the newsstand copies (or even if he has them in his database at all) when I'm doing my own pricing. It's fun to charge 95% less than what a major online retailer is asking.
I don't mind Chuck personally -- I've met him twice, and he was very nice -- and he is straight-forward in how he runs Mile High. He's not losing sleep if we all think his business model is insane. He's still making money.