I was just curious if anyone here has made a pure kensai and have him go with two-handed swords. If so, how was your experience with it?

i haven't but when i play minsc and jahiera they usually alternate between dual-wielding and 2-handed weapons - my feeling is that dual-wielding dominates in SoA but in ToB when you start getting greater whirlwinds then the 2HWs really come into their own

you'll have run out of proficiency points to put in 2H swords and 2WS by level 9 anyway so it's not an irreversible decision for you - see how you get on

Most of my past kensai have used 2 handed weapons, especially swords. I found it very enjoyable. Perhaps not the most damaging build available but still very effective none the less. The rock bottom speed factors available through 2HWS and the 4 level interval kensai speed bonuses mean that you can eventually swing the slowest weapons in the game with a zero speed factor.