Does anyone know if using a PK's of char(20) will cause a problem?

We moved to using our own GUID routines a few years back but I have
been wondering if switching to a fixed length char 20 vs. a
LongInteger would cause any problems.

Our GUID routines creates a 20 char [0..9] sequence.

I did some tests and could not really tell a difference...

Thanks,
--Raymond