Tight bends in pex need to use these
https://www.supplyhouse.com/Wirsbo-Uponor-A5150375-3-8-Plastic-Bend-Support-2127000-p
Don't see what place your asking about. I can recommend supplyhouse.com however. Awesome service and selection
As far as bluefin vs aquapex. Bluefin is pex B. Aqua pex is the original pex and is refered to as pex A.
The original wirsbo (now uponor) system called propex, uses a pex sleeve slid over the pex tube which was expanded with a special tool. After expanding you had 5 seconds or so to slip the fitting in and the pex would try to return to it oringinal shape due to its cross linking. The fittings are larger(OD) than the inside diameter of the pipe so the pipe and ring form a vise like grip on the fitting. Several advantages include better flow as crimp type fittings restrict the flow greatly due to being much small I'd than the tube. The fitting connection is pretty fool proof, if the fitting is in its good. Can't miss or under crimp. With the tube itself the cross linking is superior to pex B or C and has better kink resistance. Also if you kink B or C you HAVE to cut it out and splice. If you kink A you can work it out with a heat gun.
Pex B and later C use a different and cheaper cross linking chemical process during manufacture. The manufactures didn't feel that it needed as much cross linking as the tubing is not stretched/expanded as with the wirsbo propex system. I would stay clear of pex C.
You may of noticed I am a wirsbo propex fan. The Milwaukee m12 expander can be found for $400 dollars which turns many off. However if you keep it clean you can typically sell it for $350 on eBay after you are done. Cheaper than a pair of decent crimpers and its so much nicer to use.
I personally use wirsbo fitting with Mr Pex pex A tubing from supply house. Mr Pex was started by the engineer(inventor?) responsible for bringing pex tubing to the world. After he left wirsbo he started his own company. Cheaper than wirsbo but still more than much of the pex b tubing. Pex A can be use with crimp fittings.