I cannot say much about a hydrofoil for a 21se (because I have never been on one) but I can say I personally have not met 1 person that was NOT happy adding one to any boat they have. Now, I am not saying every boat needs one but I am saying everyone I know that has installed them has been glad they did. I had one on my 2320 and without it, the under-powered (200hp) boat struggled to jump out of the water. With it, it got on plain easily. I also added one to my 19' Kencraft CC and my brothers 17' Arima Ranger and in both cases it was very beneficial (especially the Arima). It's a relatively inexpensive addition that I believe would benefit your boat, especially if you feel you are using the tabs more than normal.