Theres no shortage of 4m seariders, 4.7s are a bit rarer. They are very different boats really, a 4m is very small, and a 4.7 like a shortened 5.4
I would go for a 4.7 if you can find one,
plenty of 5.4s around though, and you will only want to upgrade to one if you buy a 4m
go on join the sr5 owners club....you know you want to