In most cases, when using the hydraulic pumps on CUTS for a loader, backhoe, log splitter, etc, you are not using it while traveling. Or at least you are not pushing/pulling a significant load while dumping a loader for example. And for simple traveling while dumping, you won't notice a difference in speed, ground or dump. There may be a few chores that do muliple tasks whereby the pump performance could be affected. But for most users, I doubt this comprises a large portion of their work.
Also, it depends on the pump configuration. Some designs use one pump for several shared tasks, like power steering, implements, tranny. Other designs have mulitple pumps that split the tasks. Kioti's/BC's have 2 pumps. One for power steering, and one for everything else. In this way PS isn't compromised by loader work and visa versa.
The pump gpm limits operating speed, more so than hp. So, then a tractor that puts out say 7 gpm for implements does so without fully taxing all of the hp. Therefore, the same tractor with the same pump running the same implements at the same rpms will perform the same regardless of engine hp, as long as their is at least enough hp to run the pump at full gpm.
I do believe HST's are more geratly affected by pump gpm than gear tractors due to the nature of HST trannies requiring more of the gpm to function. Whereas the gear trannies mainly use hydro pressure for shifting/clutch/pressure plate engagement.
If the weight of the machine is capable of doing a certain task, then more HP will usually allow you to do that task faster.
