Jac - you make some valid points...
I'd like to enhance a few points from our perspective as an Authorized Intuit Hosting Provider.
Cost.
Costs should be a consideration with full knowledge of how a hosting provider actually leverages technology. The specific example is RightNetworks which splits a customer's data from the server where QuickBooks is running. This causes a significant limitation because many 3rd party and Web-Synced applications depending on having direct access to the Company File and the Application on the same server. So whilst the price of Right Networks looks inexpensive, it won't work well with just a few web-apps added. So "buyer be 'ware." If you just need QuickBooks, they'll be fine.
Then, you should consider if they include QuickBooks ProAdvisor level services in their Customer Service.
Customer Service.
The "best" QuickBooks Hosting providers offer consulting services in addition to "just hosting." Why? QuickBooks can be a super-critical application to most companies. It's good to know that your hosting provider can do more than hosting...but be a reliable partner in your operations, growth and care of your QuickBooks Desktop solution. Better yet, they include those services in the monthly hosting price.
See you in the clouds.