thanks! This is a very helpful piece of information!
Most recently I have programmed for Plesk, and I have to point out that their RPC API ist a large pile of crap (and their support is even worse). I have not seen a lot of the ISPConfig API yet, but I like it much better already.... ;-)
And, btw, I have seen a lot of the ISPConfig community support, and I cannot stress enough how great it is!