Not sure this was actually mentioned in this thread but you can make your own latex patches from an old latex inner tube. Just make sure they're nicely rounded.
The problem with butyl patches is that it creates stress points in the area around them, overstretching the latex locally if you like which may lead to premature leaks and/or punctures.
I actually do feel and sometimes even see the presence of a butyl patch with top of the line tyres a la Veloflex Corsa etc. I find it quite annoying.
I've used all of the latex tubes; Michelin, Vreds, Vittoria, Challenge. I find that the Vreds are a nicer ride but they are finicky. If you get a small hole and need to patch it on the road (I usually just carry an extra tube), it may be hard to find/hear/feel. I'll usually just put in the spare tube and wait to get home to patch the other one (it is necessary to submerge it under water to find the hole). I use baby powder on them before mounting them in the tire. Currently using them with Conti 4000s which give a smooth ride (contrary to using a butyl tube which makes the Conti's feel like they "bounce" over road imperfections).
As mentioned, I too used old latex tubes and cut them up for patches. I uses the regular glue that comes with butyl tubes, I've even used Super Glue. Sure, they lose air but I pump up my tires before every ride just out of habit. The reason why I have the old tubes and are using them for patches is because I could not find the hole that was causing the leak or they have been patched before and the escaping air is coming from a bad patch job which would require ripping the old patch off and reapplying it which is not idea so I just use it as patch source.