The biggest problem with shared hosts and mod_perl
is that you must completely trust all of your neighbors not to mess with your subroutines and your data. Once I can execute arbitrary Perl code, your shopping cart is vulnerable.
So you end up having to run one Apache cluster per trusted user group, and that starts getting pretty expensive from a memory perspective.
If you are looking to move to a different host location, please go immediately to Sprocket Data. I've had Stonehenge's server there for about six months, and have really appreciated their service level and price/performance ratio. Even my former ISP moved their co-lo service to Sprocket!
-- Randal L. Schwartz, Perl hacker