The errors are in mod_jk.log and there are no errors in out and error logs on any of the instances. The cf logs just stop at the time of the outage in cf (meaning no more requests are making it to server).
Memory seems fine in fusion reactor. But your mention of it being a memory issue aligns with what I have seen when googling the error. I could try increasing permgen to see if that helps, the main heap seems ok though.
Will try the 10 minute timeout.
And yeah would be interested in the native tomcat library option. I have a mixture of railo and acf clients and have no issues with railo clients on mod_jk/w2k3/apache 2.2 (though the publically released mod_jk, not the custom adobe one). So I find this very odd.