Quick background, my friend went to string his Arcsaber FB at 27lbs out of fun and asked me to try since I am using an FB as well.
Interestingly, I find it much more easier to use (I would say it's effortless to the extent clears went long a lot of times) when I used it to clear, smash and drop. Netting were also much better. Lifts were also higher and deeper. I also hit the sweet spot more constantly.
My FB, which was strung at 20lbs had a different effect. Clears required more effort, drops and smashes are decent and netting and lifts required more control. Lifts also weren't that high and deep. I tend not to hit the sweet spot at this tension too.
Why would that be so? Thought it would be better at a lower tension?
The 'sweet spot' of optimal tension varies between player and strings.
It is a personal preference issue and a balance of getting power and control. You could have a chane in power, but lose control. A player would have to judge himself of his priorities. Each player swings and makes contact with the shuttle slightly different, so the the relationship between tension, and power, is going to show a lot of variation between individuals.
The OP tried another racquet. Perhaps the grip diameter affected the assessment as well.
alien9113, sounds like your level of play and technique is > 20lbs tension. It is not to say 27lbs is perfect for you. You clearly have noticed the difference in the different tensions and find 27lbs plays better. 20lbs and 27lbs is a large gap. The question that only you can answer and it will take time, is whether you play better with slightly lower than that, higher than that, or exactly same tension.
You don't necessarily have to go all the way up to 27lbs. If you found that you played better with your friend's 27lbs, then try to go somewhere between 20 and 27lbs. Maybe try out 24lbs. The FB shouldn't break at that tension.