I believe there are Moodle Partners who are hosting companies with in depth expertise in hosting Moodle.
Yes, there are many - the partner program is regional - intended to provide local expertise (in your language, knowledge of your local institutions, business climate, etc). The recommended practice is to go to moodle.com and choose one or several of the partners in your region. If your project is not something they can handle, they'll forward your request to Moodle.com for a recommendation.
Would the level of support/expertise offered by a Moodle Partner or by a company which officially supports Moodle be *significantly better* than that offered by a non-specialist hosting company?
Absolutely, a requirement for partnership is having worked extensively with Moodle for several years, having contributed significantly to it's development, documentation, & support, etc. This means that a partners programmers, support staff, sysadmins, and management have significant Moodle knowledge. A partner also likely has knowledge of clients running Moodle implementations of a similar size/scale to your own, and thus taking their advice can save invaluable time. A partner can afford to hire, train, and keep staff with Moodle specific expertise, something you are very unlikely to find in a general purpose hosting company. Moodle is a feature rich, powerful application suite, so running it does require expertise and ongoing study/training to maintain that expertise as new versions of Moodle interact with a changing computing environment (
AJAX, Cloud computing, handhelds,'Web 2.0', Chrome, etc.)
Finally, all official Moodle partners contribute 10% of their revenue back to the Moodle core team - this is a big part of what keeps Moodle going. So by working with a partner, you are contributing to the improvements, ongoing security checks/fixes, etc. that keep Moodle a viable solution for your online learning effort.
Best
Michael