I have reasonable experience to manage my own server, so gogrid style management is not a problem. But seems mosso is a tag cheaper somewhat- except the very difficult to access compute cycles terms. Anyone could share about this would be very welcomed.
It's simple, Mosso is just like a "reseller" hosting. They provide you everything whitelabel from billing to control panel then you sell it back to customers.
If you are developer, I recommend you choose GoGrid. Firstly, Mosso doesn't provide SSH access. Secondly, if you are RoR/Mongrel user, you are capped to limited RAM (unless you pay extra in addition to $100). Moreover, GoGrid allows you to choose server image (CentOS, Redhat, Windows) with some out-of-the-box support for RoR and LAMP.
Somemore, GoGrid provides you initial credits ($50 or $95 if you use MS-WEBFWRD) for you to try out before actually paying for it.