The issue is the previous models had 12 or 15 devices for the same price or less. It's just a marketing ploy to force that other 10% to the 900. Probably a sound business decision for logitech, but bad for the consumer. I'm using 12 devices (add lights, htpc, DVD recorder, AV/Switch, etc. to your list) on my $100 harmony. If I upgrade, I'll have no other choice but the $400 model in the harmony lineup. So in my case, I'd probably switch brands altogether before I'd pay that kind of money. Even if I did, they've also crippled the 900 by removing sequences. So now they simply don't offer a model that suits all my needs. There were plenty of old models that did.
As for putting your system on a diet, I'd never build my system around a stupid remote. It's the other way around. There are plenty of remotes that can handle a system with more than 6 devices very easily, including a $10 POS remote I have. And that cheap remote can do 15 step sequences when the harmony can only do 5 steps. So just because logitech decides to cripple their new models in the name of greed, I'm certainly not going to retire any of my AV equipment to suit their misguided whims.