Only my view as somone who has been involved with a number of road racing teams in the past.
If you are riding at a high engough level, for a team and all things are equal, (Bonuses, support, team set up etc) then the only thing you need to think about is "which bike will I loose the least marks on?"
I really like the Scorpa SY250 but I would suggest (and this is only my opinion) that it may cost you a few places in an event compared with a Sherco. Finishing places are important as a proffessional rider and I would choose the Sherco.
Now, if you have to buy your own bike and run it for a season, that's a different scenario, the Scorpa may cost you less money. As a clubman myself (and not a very good one at that,) where it doesn't really matter if I finish in 15th or 20th, I would choose the SY
It's a close thing.
Try asking the Sherco team for a better deal to make your descision an equal one.