I had an '83 XS650SK Heritage Special and also several standards. The stock seat on the specials are a bit lower, I think about 29"; standards about 30 1/2". I'm only 5'5", 161 lbs. and had no problem with tip-overs when stopped with either. You'll have no trouble at all at 5'9"; besides if you do you can always double up on desserts and get the poundage up. Seriously there are many ways to lower the bike with sacrificing too much in the handling.