The Porta-Colors did indeed tend to hold up very well over time. It seems largely attributable to the low B+ and narrow deflection CRT which didn't take a lot of deflection power. Everything ran pretty conservatively.
There was one all solid state version, the Porta-Color ll
http://www.rwhirled.com/portacolor/GE-JA.htm which was a nightmare to keep running.
Bill(oc)