Do you really think GM regeneration is useful? I had troll once as a starting char but in a complete party but somehow I could not see regeneration working...
Once you develop regeneneration, do you go past GM lvl 10?As for the knight, I was always in favor of offence over defence - and knight with GM Armsmaster can really deliver serious dmg really quickly...though lacking a little in hp.
So, it basically boils down to: more hp, less dmg vs. less hp, more dmg
Therefore it might be as well a matter of preference than planning, I guess.
None the less, what is your opinion of a solo knight and solo troll