I don't think that's a bad idea at all, although personally I would go for the marantz SR6006 instead of the SR7005, it's just got a few small differences that makes me like it a little more, and if you are going to use an AVR to power your speakers the difference between the two isn't big enough to warrant the extra money.
As for the sub upgrade, I have no issue with it at all and I'm not sure what your budget is for this thing, but I'll throw out a few links for your consideration anyways
Product Listing, Availability, Status and Pricing - Seaton Sound Discussion Forum
http://www.hsuresearch.com/products/uls15dualdrive.html
VTF-15H DualDrive Packages
The first is probably above your budget, the next two probably would defeat your goal of simplifying, but you could always get a single of either.
Sublist
I've heard a few different models from this company and I was really impressed. All hand assembled stuff made out in CT. Great customer support too.
Subwoofers
Another company that hand assembles their speakers, you can get a custom finish and because they're an ID company they offer an in home trial period.
Subwoofers
I haven't dealt with this company before, they're a custom install company down in florida I think, but this is a pretty good deal on a velo so you might want to give them a call.
Theres always funk audio as well, but if the submersive is out of your price range so will a funk, unless their 15 inchers are out, but it doesn't look like it on their website right now.
So theres a few links to keep you busy
