PeopleSoft on Informix??

Our company is running PeopleSoft v5.10 - currently in the process of moving over to 6. We are running this on Informix 7.12 on Digital Unix. Now, the former DBA who was in charge of this had tons of problems tuning the PeopleSoft databases. Are things really this bad? He had told me that Informix just couldn't handle the massive number of tables, views, and indexes that peoplesoft used and was nearly impossible to tune well. I was even told not to update statistics on any of the tables because this actually broke the informix optimizer and it would choose the most inappropriate path. I'm not new to Informix, and I've done pretty well on the other databases around here, but he's got me scared to touch the peoplesoft stuff. I'm inclined not to believe some of these things, but then again, I'm not going to go playing around with the parameters until I know for sure. Has anyone else had this experience? Is it really true? If not, are there any tricks I should know to get peoplesoft running well? Thanks for your help, Jeff Diaz, DBA jdiaz@accustaff.com