The only downside I could think would be hand lag, with the interlocking grip you are less likely to have tour palms shifting, a movement 1/4 inch either way could cause your shot to drift up to 10 yards , now that is depending on what you are doing, if hitting a driver “being it is your longest hitting club” or is supposed to be, you could possibly see more of a difference with it than say your 7 iron. But as others have said if the 10 finger grip gives tou better shots than i would keep using it! Just my 2cents worth , on the question you asked. “ what could be the downside “

LOL! Okay, I have to guess you uploaded the wrong image? Or are you just keeping an eye on this post?! Pretty funny no matter what.

I use the same baseball grip just to habit from playing baseball. I think if it works for you its fine

Robert Steb uses baseball grip he’s not great but has had a successful pga career. Use what works for you.