I currently gig the 7 Pro and have a PF500, which from all accounts sounds identical to the PF800. Both sound really close, but the 7 Pro has a little something extra going on to me - a bit more weight, heft, thickness to the sound.
The 7 Pro went through a rocky period with reliability issues when initially released, but it appears those issues are long since resolved. Mine has been flawless thus far and it sees a good bit of road time. With that, I’ve only had it for just over a year (bought new). The PF500 I have and used sparingly (bought used here on TB to be mainly used as a backup) is having issues cutting in and out that they were known to suffer from. Luckily, the PF800 seemed to be immune from the same issues.
For me, the 7 Pro is the better sounding amp, but not by much.