Just came across this, and I'd be curious as well. I've been running OpenERP locally on an Ubuntu Server for some time, but am looking to move this into a hosted environment if I can.
If it's of any help, Ubuntu does now have OpenERP Server (and OpenERP client) in it's package repositories, so couldn't it just potentially be a matter of using those packages to at least get it installed, then simply apply the updates to the latest version?
I'm not currently using Hawk Host (currently everything is hosted locally), but am very interested in moving to them. And while the OpenERP question doesn't make/break the decision, it would definitely be a 'nice to have' for my needs. But like you asked, would this need to fall under the shared hosting or the VPS model? Or neither? (which is fine too).