this is an interesting topic.
We own a PG magnum and have over 2000 hours on it. Have had to replace the recoil and a few misc parts. Nothing huge. We do routine maint as per the manual states. our guy who runs it is getting dogged though. Keeps dropping hints on a t3000 as we have a turfco dealer 5 mins from the office.
IMO the PG is old technology. I personally LOVE Zero turns but our market is mainly PG and T3000s