String material is usually not the main factor in whether a string is quiet or not. How it's built, tuning, nock fit, release, etc. all make a difference.
If you used the same arrows, that could be part of the problem. Often you will need different arrows with a different string (due to a difference in string travel, not a dramatic difference in performance). If you used the same brace height, that too could be a problem. Normally you will have to make adjustment with different materials. Nock fit can make a big difference. The list goes on.
Original FF was, to me, kinda' twangy. It's been so long since I used it, and I've learned so much since I used it, I don't know if it was me or the material. Probably as much or more me than anything.
The big benefits to "high performance" materials isn't a big speed gain. Unless you are going from one extreme to the other, the performance difference is usually small. The benefits worth noting are consistency, durability, lack of stretch/creep, and reduced shock.
Over the years it's absolutely floored me to find out how uneducated some bowyers are about strings and string materials. I don't mean that as a slam, it's just a fact. Some of the craziest comments about strings I've ever heard were from bowyers that got top dollar. "The string caused the limb to twist". "Flemish strings are less accurate and can be dangerous". "Warranty is void if you use a Flemish or Dacron string" (yes, warranty void over using Dacron). Bowyers are human too, and some don't do their homework with strings, some rely on information sources that are less than accurate but somehow managed to garner a following on the www.
On top of that, you generally get a "one size fits all" type string with a bow, custom or not. It's not easy to keep a custom string made specifically for each bow. A string that will work for an 80# bow may not be best for a 30#, and vice-versa. Proper nock fit for a X-nock is going to be much different than for a Bohnning Classic.
I don't see going "skinny" as a cure for anything. In two decades of making, studying, and tinkering with strings, I can't make a "skinny" string do anything that I can't make a moderate size string do...at least not anything positive.
Chad