I have the Mk3, and besides some technical problems I had, it sounds great!!! really like my '64 Vox AC50, bit of course more powerfull. She sounds big, sweet and nice and it can be overdriven very good too!
Rob/basvarken has a PTP Mk 1. and he has some problems too. We didn't have time for an A/B test yet.
I believe there are more Orange users here.