I re-plumbed my OTAS with PEX after a kitchen remodel and used Seatech fittings. These fittings do not have a barb inside the pipe and do not reduce the ID at the fitting.
Pressure tested (air over water) at 150 psi when installed and now at 14 mos and 10 trips since installed I've not experienced any leaks period.
No tool required and easy to remove/reuse the fittings.
Quick Connect Fittings - Manifolds - Valves - Sea Tech, Inc.