The 5HP solves every problem I encountered with my 3HP. The shortfalls, to me, with the earlier models, were:
1) Not enough memory for sounds
2) Leslie sim/organ modeling not the latest/best
3) No split/layer capability
4) Limited display (detailed info, brightness, etc.).
5) HP action okay -- pretty good, but not great
My new Nord Electro 5HP addresses every one of those limitations. I can honestly see keeping the 5HP for a long time -- not sure there will be any new features or improvements that will justify the high trade-up cost in the future...