It would be a good idea for the OP to study the PL website. It has plenty of information about the amps. There is more detailed info on tube use.
Hopefully, the OP s recognizes he is being given subjective opinion i.e.-
"I guess the last weakness is that for the PL to sound its best, you should plan to spend upwards of $1000-1500 on tubes. The stock tubes are really, really mediocre."
Everyone's setup-from the room/speakers and gear will make the presentation different.
The stock tubes can be just fine to some ears. That statement is false.
Besides the power tubes,the 2 innermost(L/R)gain tubes are really the only one's worth considering spending more cash on, for any noticeable sonic change-IMO.
Different brand/topology/possibly more money, is what you're looking at- if you're comparing feature/benefit and build quality against the PL.