My former neighbour had one and swore that you needed the gasoline 2200 psi
type to make it worthwhile if you plan on
stripping old paint off.

I guess that is a good assessment. If you just want to clean the old paint the
electric 1200 PSI units are plenty.
When I rented a 6500 PSI unit I was taking the stucco off. If you are a serious
pressure washer user you would use a wider, low pressure tip on a big machine
and clean a wider swath at each path.