Returned to Bath for the first time in a while this week, and was able to make some observations of the new U1/2 service pattern.
The U1/U1X are now almost completely separate from each other in terms of PVR. Currently the PVR of the standard U1 is 11 (8 e400s & 3 bendis). These work Green Park - Uni shuttles during the morning & afternoon peak periods, only doing the full route during the day & in the evenings. The U1X has a PVR of 9 (all bendis), which normally are only used in the peaks, being returned to the depot during the day.
The U2 now has a PVR of 7 (In theory 4 purple B7s, plus the 3 from Dawson's, although Geminis are common place if either of the former venture onto the U1). Note that virtually all the vehicles are used all day long, often taking larger layovers at the uni, allowing another board to work the next trip, thus improving reliability for services starting at the uni.
The one interesting observation is that nearly all the drivers stay with the same vehicle all day, returning it to the depot/bus station or parking up at the uni for meal breaks. Although this reduces the risk of delays and traffic through changeovers at the station, it does often lead to bunching up of vehicles, particularly if a bus is late back from a meal break at the depot. It is this I believe that causes long queues and large gaps in the service on occasions. However I would say that the operation has improved since the start of the year, particularly in the afternoon peak, where if anything there were too many vehicles!!