I've got a Premiere XL4 and a Roamio Plus and the latter is significantly faster.
So I'm about to replace an aging S3 (could be the drive ready to die) and I'm wondering which Roamio to get. Given the two upper models don't have OTA I'm leaning toward getting the basic unit and possibly putting a larger drive in it. Given how readily the Roamio units handle playing content from each other it's sort of unnecessary to get a 6 tuner unit. We only rarely exceeded the 2 tuners in the S3 and I don't think ever used all six. So four tuners and an retain OTA recording seems like a reasonable choice.
They're all on wired ethernet, no wifi or MOCA networking.
I should also point out that I have a Mini and don't like the lack of multiple live tuners (or at least not the easy ability to flip between them without losing buffers). We keep that one in the guest room, paired with the kids rec room Premier XL4. That and I also have a Tivo Stream on the network, but don't really bother making use of it. I've yet to bother with playing content remotely so that's not a critical feature.
So really it boils down to the question of whether the UI speed (and other software features) on the basic unit is on-par with the others. Anyone with both a basic and Pro care to chime in?