So just to clarify: For mobile devices and other cases where you really don't care about the difference between AC and N, you can keep a universal SSID that has both AP's. I'd just recommend one specific AC one and then a universal one with all of the AP's.
You can set this up and the "smart-roam" functionality without a ZD; a ZD buys you 802.11k/v/r with ZoneFlex 9.8 and 9.9, which makes roaming a bit smoother.
At this point, the ZD 1000 is EOL'ed supporting FW 9.4 at the latest. It won't support the R600, and FW 9.4 is really old for the 7372 as well.
So like you, I'm a home user as well. I've got a ZD1100 + R700 + R600. I used to do a combo R700 and used ZF7982 network, but the annoyance of clients roaming from AC to N eventually drove me to set up an AC-only network. It's a pricey setup, but at the same time, being able to reliably serve my 120mbit internet connection to all my clients at full speed has made working from home a ton more productive.
For your last question about Xclaim: The Xclaim line hits a great price point, and gives you central management without the need for a controller, which is cost effective for us small-timers. But you still won't get 802.11k/r roaming support (you'll get the equivalent effect of running all your AP's standalone), whether or not that matters. Also, there won't be any BeamFlex -- the Xclaims use traditional omnidirectional antennas, not an adaptive beamforming antenna array like the ZoneFlex series. For me, I live in a crowded apartment complex where my last omnidirectional AC access point basically had a 6 foot effective range, and even if I am just slightly out of sight of the access point, speeds plummeted due to interference. ZoneFlex has been a miracle in being able to combat this interference. My old 2 AP setup was lucky to deliver 10-15mbits to the far corners of my apartment. Now my R600+R700 delivers 200mbit or more of AC throughput everywhere, as well as 50mbit even outdoors around my building!
My recommendation is that it's most cost effective to stick to your setup, and investigate setting up smart-roam and bss-minrate to see if you can encourage better roaming. And in the long run, consider replacing the 7372 with a R500 or R600 to homogenize.