I have formed a personal relationship with my Internet Service Provider because I believed that when something on your site or a clients site malfunctions, the problem can be sorted out much quicker, and much more pleasantly.
Here are some of my experiences: I recently developed 3 new Joomla sites for clients. managing the front end was simple - I was able to build the sites on a FREE test server - space donated by my ISP. Once the sites were approved "off line", they were then transfered to the main online system.
However there were some interesting incompatibilities that arose.
(1) Joomla version inconsistancies. Templates that were designed for early versions of Joomla 1.5 - trying to run on newer Joomla 1.5 versions.
(2) Lack of access to the Administration area.
(3) Editing failures
(4) Upload failures
(5) FTP access failures
All of the above were solved almost immediately.
The only problem I still have is that neither the ISP or myself can upload a forms module to one of my sites. Upload went well here in the office on my Wamp Server - but the upload fails on the ISP Servers that have Linux Operating Systems - Bummer!