xpl v3 vs. v4

[Mark Garvey redactor@xxxxxxxx]

I have been a xy3 user for quite some time. Never seriously considered
switching to xy4 until I heard it has better memory management--i.e., is
capable of handling bigger files than xy3. This feature appeals because I had
been using xy3 to massage large--approaching and, in some cases exceeding 1
meg--text files. To this end, I have a set of fairly lengthy and
much-sweated-over xpl programs, all done in xy3, of course.

My question: Assuming I were to consider going to xy4 for the purpose of
massaging these big files, what kind of modification will be required for my
programs? I don't mean specifically, but, in general, am I in for a real Old
Testament, temple-clutching headache or will the transition be not that bad?

Many thanks for your opinions.

Mark Garvey