you probably want to have a top speed home connection with as many Mbps upload speed as possible.
considering that most Maemo packages are reasonably small (the former Firefox the largest one i came across so far is about 15MBs, but you obviously don't have to mirror it) you probably may want to throttle individual bandwidth to such a level that the average package download (when that bandwidth is available) doesn't exceed a few seconds.

also worth checking is your provider's "fair use policy" which may include monthly (or daily) caps. considering that a lot of consumers are using torrents, the number of connections may (or may not) be okay.

EDIT: the home connection may still be a problem if your IP address changes.
this usually doesn't happen if your server remains on-line and reboots quickly (before the IP address is allocated to another user) but ISP terms & conditions usually stipulate that the IP address is not guaranteed.
you may also want to spent some time configuring a firewall.

EDIT2: Pali, i hope you don't mind me mentioning this here, but...
that is one of the problems that was at least alluded to on the council thread; i.e. organizing & financing hosting. home hosting is a possibility, but it obviously comes with the cost of having to manage the server; like: RAID or @ least good backup & ready to replace a HD on a moments notice, et cetera, et cetera, et cetera...