I converted mine about three months ago and have had no problems. As long as you run the ac at least 2-3 times a week, the seal in the compressor will stay lubed, and no freon should be lost through the seal.

If you go long periods of time between usage of ac, the seal in the compressor will shrink, or develop a tiny flat spot where it sits most of the time. Then under engine load it spins the shrunken, or flat sided seal, letting freon/oil by, you can see evidence of this on your under hood cover above the ac compressor (if you don't have belt cover on).