I think that the 2 above posts point out what I was thinking when starting this thread: 10 IP adresses are very quickly reached, even at home. Funny, chances are that you use less IP adresses in a small office...
Regarding the concurrent connections limit, I didn't saw that at first, but it's another stopper.
Now regarding why I do have a reverse proxy and multiple web sites, the answer is quite simple. I use vmware server, and those machines are free. The reverse proxy allows me to redirect traffic based on headers, which means each web server only host 1 site, which is easier to configure, allow to swap one vm with another to replace it without impacting the others and so on.
And why do I do it at home? Well, to learn how all that stuff work, and to host private sites, used mainly by my family to gather/exchange photos.
The point is that I live in France, and I have a permanet access with 1Mb upload and 8Mb download, international phone calls included for 30 Euros per month - this is about 37 dollars.
So, the point seems clear: the 10 IP limit is overkill. Hope astaro will change this... In the mean time, I'm back using smoothwall, and testing endian...