need to upgrade to OS 10.4.8, will FH break?

Hi all, finally hit the enevitable stumbling block.

I need to run Aperture1.5 to increase my crazy workflow (pretty much a must have app for me right now)
trouble is it needs Mac OS 10.4.8 to run

big stumblig block for me is my reliance on FreeHand MX to make my living (same goes for most of us here I guess?)

I have been resistant to upgrading up to now as FreeHand runs like a dream on Panther 10.3.9 and well if it aint broke!

my question is, what do I need to do, or more importantly what do I need to not do when upgrading:
ie. do I throw out any pref files or other files (not just FH but OS wide) before upgrading?, which is the safest choice of upgrade (full or just upgrade)

a lot of you have been through this already and I really need FreeHand to not break on me right now

any issues with older FH files? I have 10 years worth of FreeHand files starting with FH5.5, I have a lot of old FH7 files which open ok right now, but I believe some people have had trouble opening these under Tiger?

If someone can give me a blow by blow of the Tiger FHMX issues, I would be grateful beyond words

cheers, Rob

btw, I am using a dual 1.25ghz G4 MDD, if that makes a difference?