I have found that suitability largely depends of the standard of cricket played.
Against real quick bowlers it is essential to have a bat that you can wield with relative ease, as reaction times are much less.
I believe this is why big guys like Flintoff and Pietersen used/use bats around 2.8. Obviously they could use much heavier bats as they are built like brick (No Swearing Please) houses but against the sort of bowlers they faced the ability to react in time is more important.
I use a bat currently that is bit too heavy for me, but im not playing at a very high standard so find it doesnt really matter. If you can just get on the front foot to drive and even pull bowlers then it will be fine, in this case using a slightly heavier bat can even help. Ive found that on occasions ive faced a bowler who can test me out,either through pace or movement, that the bat then feels to heavy for me.