It is very difficult to actually avoid doing this, btw. And also most modpacks over time gradually fragment their ID space, becoming progressively unmanagable. Every year or so it's good to reset. If you don't like this, you should demand a full refund from FTB. I'm sure they're good people who will give you your money back!
In any case you need a map reset for 1.6.* anyways because of forge changes. May maps will not survive the transition well (boilers explode, etc).
LOL "Every year or so"....since I been using FTB since around November of last year, lets count the resets.
FTB Retro
FTB Ultimate 1.4.7
FTB 1.5.2 Beta
FTB Unleashed
Sorry I never was that good in math class is that more then once per year? This might just be the "or so" part.