You'll be surprised what those little screws can support. But anything really heavy probably and should be supported with additional hardware of some sort, I might say anything over 100lbs. But if it gives you more sleep at night have a ball with whatever method you want to use. But really most of the time if it comes with rack ears thats all its probably going to need.
+1 for rack mountable products. It's not a major buying decision for me, but for those that have racks, it's a clean way to install the product and MUCH less expensive than buying shelves.
Seems to me that the incremental product cost of doing so would be minor--just a few threaded holes in the side of the chassis. I would have no issue is the rack ears were an extra $30ish, so not only would this satisfy a reasonable number of customers with little to no impact to those that don't need the feature, I think this could also be a bit of extra revenue for Emotiva. Instead, it looks like I'll be giving Middle Atlantic more money.
I'll even throw out one more thing...why not make the products conform to RU height dimensions?? Again, for those with racks, this adds complexity and expense since one has to purchase a $100+ shelf to get a clean installation rather than a $45 standard shelf. The best reason I can think of is those that are trying to cram these components into more typical furniture stands where space is more of a premium.
Though rack ears are quite strong, I would agree that the amps aren't something I'd probably use ears for...but everything else is fair game.