I will try to answer as best as I can, but without trying to quote every post and comment.
The "user error" to me, is the addition of the external SATA drive, disabling or crippling the "whole home" portion of the DVR service, not the actual user's button presses. I'm sure you can fully operate the units without much difficulty as any regular user could operate the equipment. It's my opinion, that the addition of the external drive, which I think is causing eci so many problems, is the root of all of his problems. From an engineering POV, I think that there is an issue with the amount of buffering needed to go from an external drive to the DVR, then to the remote client.
I do not yet have Trio in MY particular home, but DO have access to seeing it in a customer home now. The client response was as fast and seamless as if using the main DVR, and no, there was no slowness or sluggishness involved.
With a live program on the client, the sequence was basically [Record], confirm [A], [QuickMenu], [Select] (the new recording was at the top), and then it was streaming. It took about 10 seconds to go from watching live to have DVR control on the client STB for me as a novice user of the system.
Pulling up other recordings through the client STB, we had full control of playback with four different playback speeds. An hour show took somewhere about 20 seconds to fully fast forward through to the end at the fastest speed. The only "issue" I saw was that FF and REW playback on the screen is not smooth (you can't follow the fluid action, its more like jumping chapters), and at the higher speeds, the show would jump in multi-minute increments.
I do agree, whole heartedly, that if you upgrade, keep an existing DVR for sanity and comparison. The Rovi interface has a lot of great features that the Trio system was not built around that some may find different.
PPV - I didn't see this in person, but the owner said they ordered PPV as part of their testing, and had no problems on either the main DVR or any of the client STB's. It worked just like any other STB. They did mention they had to go in and set the parental controls, but they never saw an issue with viewing PPV on the client or DVR, or either.
Series recording and errors. I can't comment specifically on those since I have no experience, but the system was built and based on SARA from several years ago. Some people do have issues with recording on SARA, in my experience, due to multiple recordings and conflicts that will drop anything if the two tuners are in use. Rovi, is much better in resolving conflicts so that if you use the guide, it will give you the NO symbol (circle with a slash) and allow you to set priorities, based on list position. AFAIK, Trio doesn't have this feature, and maintaining multiple recordings can get dicey as conflicts happen, but with no conflict management, you never know until you try to find a recording that didn't happen until you look for it.