Enough Performance?

All:

I have been asked to help with a Domino upgrade on a 170 model 9406 V5R1. 
Currently, this iSeries has 3 partitions on it running R5.0.12. They want 
to move to R6.5.3, iNotes, maybe a Domino intranet site. The partitions 
aren't really being taxed, in that one partition is running mail, SMTP, 
and the like and the other two partitions are running "some sort" of 
Domino CRM system. Each of the other 2 partitions are running the CRM but 
for one specific area of the company (for example one partition is running 
it for the Canadian division and the other for the US/"other" divisions). 
They have plenty of DASD, and I am waiting for the RAM.

What else should I be looking at? This 170 is doing nothing but Domino 
tasks. Everything else is on their 820. I just want to make sure that 
putting R6.5.3 won't tax this iSeries too much, at least not so much that 
the users are directly impacted.

Thanks.

Gregg