We host moodle for our course creation, and Joomla as our front end. Pupils/staff have OWA (again hosted on Exchange) and I have a great little ASP script that allows access to pupils/staff to home dirs... to allow downloading and uploading from across the net.
Moodle uptake is really growing, thanks to our SLT and various other teaching staff really seeing the benefits, we have a VLE Co-ordinator (a maths teacher) who is leading the training for Moodle.
I personally think if you have internal support, then go for your own internal solution, when the net has been playing up for us we are still able to send email and access our moodle courses.
Setting up Moodle is fairly straight forward ( I have some notes if your interested) as long as you have a forward facing IP and have sorted out your domain name then you are already halfway there.
I can see the benfits of capitas leraning gateway, but for me its too pricey and slow, my sons school use it and its never working properly..