Little backstory, I've played with the BLX90 ever since I started tennis a few years back (not a smart choice but it was the only racket I could use given that my brother plays with them). I advanced pretty well and got most things down soon enough, however my inexperience still remained and I more than often hit outside of the small sweetspot or am a bit late when it comes to returning (although it remains the finest racket to hit one handed backhands with)
Recently I came into a bit of money of my own to spend and I narrowed it down to the Wilson K factor Surge and the Dunlop Biomimetic 500. These rackets are very similar to each other with the biggest change I noticed being the spin - simply unbelievable compared to the Tour 90. Especially on doing second serves I can hit the ball as hard as I can and it'll always go in, and usually with a much much bigger kick. With the tour90 I usually had to tone it down a bit, do more of a looser grip and even then I would still miss a second serve 1 out of 5 times
So yes, the heavy top spin is great but to achieve it I feel I have to force my swings a bit more, and especially with the grip I have to hold it a lot tighter otherwise my racket won't keep steady on contact. But with the tighter grip I can't seem to do natural swings anymore like I did with the tour 90. I used to hold this one with a lot less grip and the racket head speed would usually be enough to keep the racket steady with it's weight and/or balance
So now my question is, am I supposed to hold the K Surge tighter compared to the 6.1 90? Or are there some other tips I can use to keep that natural swing throughout, thanks!