Take a look around the wowace forums, and you'll see the opinion of its regulars on "fanbois". Fanbois are always calling for a mod to be "Ace'd", asking when a mod will be available through WAU, don't even know which of their mods use the Ace libraries and which don't (since mods on the svn don't have to use the Ace framework, and there are plenty of good Ace mods *not* located on wowace), and don't know a good mod when it bites them in the butt because it's not "ACE".
Whatever you do, don't listen to the fanbois.
Mods are your work to do with what you please. If you want to code it one way, that's your prerogative. If you only want to release it on one site to keep up with bug reports, comments, feature requests, that's up to you. More sites = more work for you.
Everything you've heard above is true. There are updaters like WUU and others that span multiple download sites. Your mod doesn't have to be "Ace'd!!1!11" to be on the svn.
Word of mouth is what will gain your addon popularity, wherever it is located.
Above all, write addons for *YOU* - not to try to get every single wow player to use it.