I'm normally a "rebuild it" kinda guy, but used bikes are so cheap now, I'd probably sell it and buy a similarly priced used bike. (Unless you have an emotional attachment to the bike)
I recently saw a '01 M900S for $4900. Between the power and suspension upgrades, and the better resale value of a 900, I think you'd be ahead even if the bike is a year older than your M620.
I think #3 is a no win situation. You'll put a lot of work into the bike, have no working ride for a while, and be lucky if you break even.
Option #4 doesn't sound too bad if you wanted a new bike, or was even thinking about selling it. Kinda the same outcome for you as #3, except that you'd be selling a new bike and not a crashed and rebuilt 2 year old bike.
--Fillmore
I recently saw a '01 M900S for $4900. Between the power and suspension upgrades, and the better resale value of a 900, I think you'd be ahead even if the bike is a year older than your M620.
I think #3 is a no win situation. You'll put a lot of work into the bike, have no working ride for a while, and be lucky if you break even.
Option #4 doesn't sound too bad if you wanted a new bike, or was even thinking about selling it. Kinda the same outcome for you as #3, except that you'd be selling a new bike and not a crashed and rebuilt 2 year old bike.
--Fillmore