I use carbonite, which has a built in guest tracker similar to quest helper, but uses a lot less memory. It has a ton of useful tidbits and trackers in it that can be turned off or back on in the options interface(easily accessed). And is compatible with many other addons. The quest tracker is very useful, and the "cheat" portion of it that tells you where to go and what to do can be turned off and it'll just track your quests, another sort of hidden feature is that it'll keep a memory of quests you've done in the past(after installation) so you can refer back to see if you've done a particular quest. It has a voice notification and will spam party/raid channels about task completions for quests. This can also be turned off if you want. It also had many map mods that I find usefull, but can also be turned off if you wish. As far as I can tell there isn't anything in it that can't be turned off.
You can find more specific information
here.
But, as far as having issues, I haven't had any problems with any trackers. I've even turned off carbonite temporarily from time to time to see what Blizz has done with the in-game one and no problems.