I know this is been already debatet, i actually Red a lot about this topic, including an exel file founded here about brand kite and bars.

Own core, and i d like to buy an fx8m 2016. Core has high v and cabrina a low One. I could demo the kite with my bar on a 25 knox, Just on the Sand.
My bar had 24 metres instead of 22, i felt the kite very very good in control, landing and turning. I found It little bit slower in turning than i expected, but totally fine.

But i could not do the final and most important try as the kite was not mine and i did not need ti use safety release.

Anyone experienced or wanna comment?

Hi i own core and switchblade also.
recently received a new FX and after 3 hour in good wind sent it back and changed to switchblade. never sent anything back before unhappy.
Kitepower sydney guys realy helped me.
found the 8mtr fx felt like a 10 mtr switch in air as fare as speed and power and wind range was less than
any other 8 mtr ive ridden.
one thing ,they do turn fast, but unless your going to really through an fx around hard doing tricks etc i would test ride first or go to switchblade.
friend who is same level as i has to put his 10mtr fx in air fully powered when im 1/2 on my 8mtr switch.
After i told him i had sent my new fx back he admitted that the switch was a better kite.
try giving guys at kitepower sydney a call and see if they will send u a demo kite first to try or go to demo day.
As fare as bar goes you can check bar line lengths on core to carinha and if u can borrow a bar from cabrinha 2015 -2019 of someone on beach and do a core bare to carinha bar test,that will tell u.
2015 and up bars work on carinha,and 2015 bars are around $200 which maybe better as if u loose the core bar they are expensive.

The older Core bars flag to both front lines and the newer Sensor2 bar partly flags to one front line but still keeps some tension on the other front line. Hence if you activate the safety release it may not flag a kite properly that has been designed to flag on only a single front line (nearly all 4 line kites these days).