I've been dealing with J2O hosting for a while, so here are a few more options you might consider.

Hostpointe:
Our relationship with hostpointe has been good in the last 6 months. We have had some troubles in the past (ie no backup of our data and extended downtime) but for our needs no one can beat the prices and I believe it was an anomoly.
http://hostpointe.com/content/solutions/shared.htm

OC Hosting:
We were with them for a number of years and had very little trouble considering the size of J2O. In all respects, we are a large site for a shared server and after a while they essentially wanted to make us upgrade to a "semi-dedicated" server.
http://www.ochosting.com/shared-host...ix_special.cfm

Hostrocket:
J2O has never been hosted here but my father's business website and my Aunt's handmade furniture website have been hosted here with very little to no trouble. However, it is also more like that problems would have simply not been caught since neither website receives traffic like J2O.
http://www.hostrocket.com/products/index010.htm

Should you have any more questions feel free to private message or email me.