I don't see how it could hurt. Considering you're in a heroic raiding guild, I'd assume that progress is pretty important and that you'd want to maximize effectiveness to kill the most bosses. I have no experience with the add-on, but as long as it's pretty simple and lightweight, I see no reason why not to try it out. If it doesn't work out, it doesn't work out.
Our guild rules specifically include 'have all required addons installed', which they accept upon joining the guild.
While you should obviously try to avoid changing things like thisfrequently, I think a 2 week warning is more then enough. Also take note of the players that comply promptly, compared to those that have to be dragged into it.
Just make sure that people know that the addon is a very easy and large help when it comes to making the raid leaders life more tolerable. If people still aren't using it and repeatedly keep messing up cooldown cycles etc then it obviously means they have no respect for you, nor the rest of the raiders and taking someone more dedicated will surely yield better results.
Raiders in heroic raiding guild should recognize things that are being done for efficiency (read: to make kill stuff easier) and comply. It comes down to disciple, respect, and commitment towards the goal of progression.
TLDR....it should be fine, if suckas have a problem with it, then maybe they shouldn't be in the raid group.