I have had the Thunderhorn 2 piece,2 bowbolts,2 connexion hinges,a Widow and Big Jim locket socket,A few brass and stainless steel sleeve styles and the GN Jacknife.
I think these are all good systems.
The Thunderhorn is very meticulous and amazingly crafted.It does requite a couple small allen bolts and wrench.So a tool is required.Superbly done.Its expensive.So it may be cost prohibitive if your on a tighter budget
The Widow, Big Jim and Caribow locket socket is proven and secure in my experience.
The bowbolts slick and adds few ounces of weight.I would use all phenolic in that one as Irish elluded to.Mines all phenolic.I like it.
The Connexion hinge works well.Titanium screws in the right size are a must for installation of the hinge.I got one currantly and it functions well and is well done by the bowyer.The hinge is recessed in the riser overlays.I use a rubber roll on grip for that one.The bow with the hinge will flop around a bit when unstrung.My only complaint on that one.
The Fox Breed I had,had the brass and steel sleeve.It was solid and strong and that system does add more mass weight than any other.That can be a plus if you want extra weight in the riser.The grip on that bow was built up into a locator style grip with bondo or something so it was comfortable.Wes Wallace does the same thing with his Royal longbow,locator grip.Most you see have the straight grip which I do not care for personally.That one may be a bit frigid in very cold conditions it would seem.
The jacknife is very slick and proven.It works particularly well with the bushbow,critter gitter,traditional longbow and Fireball.Its a reliable system and can only be found on GN bows I believe.I like it alot!