We are a long-term Iris customer, including Iris Hosting. Their Claranet-based platform has become unsatisfactory and I was looking to move to Hosted Accountants, who seem good. However, HA is not allowed by Iris (since they now have a partnership) to deal direct with any Iris customers. They have to go via Iris. So we are moving to Hosted Desktop UK who check out very well. I'm looking forward to the change.
So in summary:
1. Avoid Iris
2. Look at HA if you are not an Iris customer
3. Look at Hosted Desktop UK