Oh dear, all sorts of long and lengthy posts are going to be unleashed now.
From my hazy memory, when F16 came about it looked at existing hi-performance 16ft cats (ie Taipan and the Stealth) and looked at ways to equalise performance and create a level playing ground. This meant that new designs had a basis to look at, rather than competing on design and being same same but different (had to throw that in, been in asia for a while). But F16 went down the path similar to F18 in trying to ensure all boats meet a certain "box". This "box" is different in many ways to other "boxes" which makes the class more or less attractive to different sailors.
F104 from what I can see is to move some of the parameters of the box around, but saying you must rate in this band to join our group, but we are flexible on this and that.
Each horses for courses and could be endless hours of internet debate. But end of day, lets promote sailing and go out and do it. I know that this weekend will do a passage race on Sat and Sun round bits of Singapore. Lining up one girl to take for a sail afterwards as she is getting the sailing buzz. What are you guys doing?