I am relatively new to the PVR side of MC. It looks like a promising start, but I don't think it justifies a new quad tuner just yet!
I always ran standard firmware on my TF6000PVRt because it was a little different to other models, so third party firmware wasn't as good. I ran TEDS Suite on a separate PC to select programs to record using rules, and then sent the recording schedule to the Topfield. It worked, but it was an extra piece in the puzzle, and required maintenance. However one of the reasons for switching to MC was that I wanted to record HD channels, and I didn't want to buy yet another limited hardware PVR, particularly as in the Australian market no-one seemed to be able to supply a stable, reliable HD PVR. I built my HTPC for JRiver MC, and I was lucky to be able to buy a PCIe Quad tuner here in Australia for a very reasonable price. Unfortunately those aren't available any more, so I hope mine lasts forever!
I really like the all in one solution that is JRiver MC. The recording rules in MC are now better than TEDS Suite ever had. Far more flexible and accurate. I think MC now does better TV, including PVR functionality, than the Topfield plus TEDS Suite ever did... Well, except for reporting issues like missed recordings, failed EPG data collections and loads, etc.
I looked at NextPVR Bill, but just didn't like it really. It was still a big compromise, and only part of the solution, which you have discovered. As far as I am aware, it sources EPG either from OTA, or using XMLTV sources, such as Grabbers. MC can do all of that as well, with Rovi, PercData, XMLTV, and ATSC OTA EPG collection (USA only). I use EPG Collector to collect and enhance OTA EPG data in Australian, then import the resulting XMLTV file. Works very well. Microsoft's Rovi data has been unreliable recently, which is an issue. Microsoft just don't want to be in the free EPG business any more, except perhaps for the Xbox, so they aren't interested in ensuring Rovi data is reliable.
JRiver has
Web Gizmo for remote access, and JRemote. Not a full web interface, but you can schedule recording from any PC that can access the server. Plus of course if a PC has MC installed on it, or you carry around a portable installation of MC on a memory stick/card, you can access that full interface from anywhere. Perhaps none of those are as convenient as a separate, full web interface, but functional.
The trouble with MC is that it does so much, but isn't documented very well, that people never find what it can do.
Anyway, I'm sure recording multiple channels from one broadcast stream will come along eventually.