g'day Mike
I don't have experience with either reel - But I do have a 6500 (on a BWS 8-9.5kg Ugly Stik) and the reel is really a bit HEAVY - Though I do like it, I'd rather have the 4500 as a general purpose b/r. I use mine for floatlining both snapper and mackerel and for my purposes I think the 3500 is a bit light . With the 2 drag systems they are all relatively heavy reels though.
FWIW
Tony