Eppo's point on the demo is the key, any review just helps to narrow down the field but the demo is the critical step in final selection.
That said you can waste half a season demoing gear before you make a decision and depending on your experience this can be a little flawed as well. As an example when I decided I wanted to get onto a surfboard I tried numerous brands, problem was a surfboard under a kite was new to me so with each demo my skill level was also changing. In the end I based my final decision on a mag review, demo and price point. Happy so far...
Guys
As a team rider, you will be biased to the brand depending on if you get gear for free asa Grom or really love the brand as a senior sponsored rider.
Opinions will differ depending on which sponsored rider you talk to, but as for myself.
I like to go through the points of difference in my sponsored brand compared to competitor brands and always recommend the kite shape that is suited to the rider and what they want to get out of the sport.
I also encourage them to try other kite brands so they can validate the points of difference that I believe and then it has to be upto the individual to chose what they like.
Bias is not something you can tar everyone with the same brush.
Some sponsored riders will be at the red thumb end of the scale and others at the green thumb end, same as shops, same as magazines, same as instructors.
Personality and honesty usually sort the tools from the genuine people.
As a shop my call on this topic is that sponsored riders should do 2 things.
1) always declare the brand they represent - not doing this is plain dishonest and; for most readers; downright insulting as if its biased the bias will be obvious.
2) they should stick to giving a really indepth breakdown of what kite XYZ is for; who it may best suit and how the design matches and achieves the result the manufacturer is aiming for.
When it comes to their personal opinion of how good it is then it becomes a matter of their commitment to the brand and we should all take that as just another single riders opinion AND one read it as one review which MAY be biased towards their supporter (obviously).
Anyone who buys solely on one or 2 reports which may or may not be sponsor biased deserves the consequences we all face when making uninformed decisions.
Research long & wide (critically assessing each review) and demo demo demo.
No kite does it all and whats right for one can be the worst choice for another.