There was no hard 4gb limit on file size per se. The 4 gig limit applied to the amount of system Ram the 32 bit version of the program could utilize, which could in turn affect how large of a file systems could comfortably work with.
That said, yes. A 4gb file is quite large, and could cause stability problems on many systems. 4gb file size is well past the point where I could even reliably save files in 4r7.
Supposedly R8 has improved performance in this regard with large file sizes, but I would still avoid letting them get that large if at all possible.