I have 7 instances from 8.1.5 to 8.1.7 on RH 6.2 and 3 instances on Solaris (+ 1 RAC 9.0.1) + 1 instance RH 7.2 with 9.1.0 in development env.
I haven't any problems with this databases on Linux except one
(8.1.5, but it was unstable version of oracle)
avg uptime on production servers 4-6 monthes, like solaris.
now i going to install 9.2.0 in rac on RH 7.2,
(i like desicion with Suse + Rac 9.2.0, but this is not my stuff).