If you do not have any error, I would not.
Until very recent (when Apple stopped including gdb) that was used by everyone on mac.
And the IDE has been adapted for 6.3.5 too.
Apparently on new Macs the newer GDB do work too (I have not tested myself, but long ago, on a very old Mac, 6.3.5 was the only thing that worked.)
You can try, but keep the old one.
Also, if you try there may be differences between stabs and dwarf (in the project options), and it may depend on the version of the linker used.
If you have specific issues that are not listed here
http://wiki.lazarus.freepascal.org/GDB_Debugger_Tips then you should post them.
-- EDIT
for 32 bit cpu 6.3.5 is certainly good
on 64 bit cpu (debugging 32 bit apps) 6.3.5 has the "timeout issue". The IDE deals with that, but occasionally there may be a variable that you can not inspect.
If that is an issue a newer version may help, but it may also not help.
Certain variables can not be watched with any version of gdb, on any (or most) platform:
- resourcestring
- array of record ... end (when the record is declared inline, and does not have a typename) "array of TMyRecrd" should work
- ...