Re: strat bridge replacements?
if I may ask what specifically do you dislike about your existing two point tremolo system? what are you hoping to achieve by upgrading?
I can tell you right now from experience the graphtec saddles are all hype, I rarely break strings and I played an 02 American Deluxe strat until a year and half ago. They never improved tone on any guitar I'd tried them on, and since I didn't really break strings in the first place I never noticed much difference with them improving string life.
I prefer vintage style saddles made of nickel/brass any day, the graphtecs really suck a lot of life out of your tone for lack of a better word.
My favorite modern tremolo design for a strat is the G&L Dual fulcrum, this is what I'd advise you upgrade to if you make an upgrade, just beware you may have to do routing.
I think the trem block would make a bigger tonal difference personally.
I used to play strats all the time (really out of all my guitars) I haven't broken strings in years. If you play with half decent technique and have well setup instruments string breakage really shouldn't be an issue. I don't even break strings when I try stock guitars out (strung with 9's), this is coming from a guy that usually plays 12's and 13's.
I should add that it's important to set the saddles radius to match the fingerboard, use a well cut bone nut, and set your intonation properly. Once you get your strat setup well with the tremolo action and all those mentioned items you should be home free.