I think it depends on who is selling the amp and whom he is selling to. A PCB circuit is more compact and faster to manufacture for mass production, hence cheaper and faster to produce. Definitely a good marketing and selling point if you are a PCB circuit manufacturer trying to sell your product to the amp manufacturer or the amp manufacturer trying to sell it to the retail or public.
On the other hand, the PTP circuit is much more easier to make modifications and diagnose if something had gone wrong. You can change a single component easily if you want to. You usually have to detach the PCB to get to the flip side when you try to diagnose or follow a circuit, which is very combersome and dangerous when you have the power on. A nightmare for the service tech.
If the amp is all solid state, then it probably will last long provided that its components do not suffer early failure. A PCB will have its advantage in this case.The heat that are generated from the tubes in a tube amp will definitely do a number on its components and some of them may fail earlier than they should. You can easily spot that component and change it if it is PTP. It is more difficult spot the failed component if you have a PCB and you usually end up changing the whole board because it is not practical if not impossible to change that component.
