I have yet to try Ic3 or Ivans 1.0 but my "base camp" is Sense-able 3.1 (
[ROM]Sense-able 3.1! OverClock [5/10/10] - xda-developers)
I have tried many other ROMs looking for stability first and functionality second (all the things that should work if I had never rooted) then all the fun stuff like OC and wireless tether are the last on my list. The icing on the cake if you will.
I have flashed so many ROMs and spent so much time getting them set up the way I like them only to find out I have to flash another zip to fix the mms or gps, or there is just something basic that doesn't work that I cant stand it any more
I have been running Sense-able for months now

(which means I am not exactly up to date with all the latest versions of all the ROMs) and as long as I don't go crazy with mixing things like OC widgets and Launcherpro (which sounds like it is a problem on any ROM) I have ZERO problems.
Last thing is the most unfortunate: Sounds to me like every Eris has the
potential to act differently for every ROM and every user. So there is no "word of God" regarding what will work best for you.
Just remember to do a NAND if you have made progress I like to rename my NANDs with some description (e.g. latest_senseable_minus_oc_and_extras or ItAllWorksButNav)
Note that you cannot put spaces or other special characters in the name of the NAND besides underscores or it will not be recognized when it comes time to do the restore.
Now I am going to try Ivans 1.0 because it sounds like the perfect ROM for me.
Oh, and I will say that OverClocking has caused more headaches for the minute gains it presented than it was worth. Watch your battery life and compare it to the actual performance "gain" and you be the judge.
Good Luck, and above all Have Fun!