I had a Rogue Cronus Magnum and a Cronus Magnum II integrated at one time, notice I said had. I felt they inserted a tiny bit of grain into the music. I noticed it first with the original Cronus Magnum and thought the II version would be better. It wasn't, the grain was still there and once I noticed it, couldn't get past it.
The PL is in a totally different league, it is an amp you can use for years and never be dissatisfied, they are that good. PL claims 10,000 hours on the power tubes because they run them with less voltage than other amps. I heard an EL34 based PL amp which was very addicting sounding, and then my friend bought KT150 tubes for it and WOW, the bass was to die for. I am an older audiophile like you and if it was going to be my last tube amp, I would go for the PL. For myself, I went back to McIntosh solid state which is almost as good as tubes but not quite.