Personally, I never use Festo fittings on ANY connections, I just dont trust them. Yes they most definately make life easier when working on the airplane thats for sure, I had a festo fitting on a UAT fail, sucked air, flamed out. Landed fine, took me a lil bit to figure out the fitting itself was the culprit. Now All I use is barbed fittings and tees, with safety wire on EVERY connection.
here is a good post on this very subject
http://www.rcuniverse.com/forum/rc-j...-fittings.html