What are the differences between these bikes and their superbike cousins? In the case of the Felt, it's the front end, fork and stem. With the PRfive it's only the stem and the frame lay-up. Yes, of course, the components will change, but the meat of these bikes is the frame.
Now, that's not entirely true. On Slowtwitch was a piece a month ago
about the inside of bike frames, the stuff you don't see. Felt's FRD frames are extremely laborious to make, they're lighter and stiffer, and this is the sort of process that generates an S Works decal on a bike that otherwise looks exactly like a bike that bears a Specialized decal. The IA 1 uses the FRD process. The IA 4 does not. Aerodynamically it's identical, but its weight is not. The IA 10, 14 and 16 are going to use this same Aero Tri UHC Advanced Carbon Fiber schedule and while I don't know what that precisely means, it sounds pretty good.
The IA 16 starts out costing just under $3,000. For an extra $1000 you can buy an IA 14 and you will move to Ultegra derailleurs and a little up-spec'ing of FSA and Vision crank and brake calipers. Let's imagine spending that $1000 differently. First, I might ditch the FSA front caliper and replace it with a TriRig. Felt makes perfectly fine aerobars, so they're not an upgrade target unless you personally find them an issue. What I might change are the extensions. I'm very picky about extension shapes and tactile feel. The $1000 difference between the 14 and 16 also includes a different rail on the Prologo saddle but will you like that saddle, regardless of rail? If you're going to change the saddle to a Cobb or ISM anyway, who cares what came spec'd on the bike? Same with cranks. Are you going to stick with the stock crank arm length and ring sizes? Are you a fan of Rotor or Osymetric rings? Or of a particular crank-based power meter?
If you make all these changes just about the only meaningful difference between the IA 14 and 16 are the derailleurs and, honestly, there is no shifting difference you could divine. Is there any performance difference? Minor. Maybe a longevity difference.
In my mind, the IA 16, the way I would set it up for me, new front brake, extensions, maybe crank, a new saddle, is somewhere between a $3600 and $4000 bike, not including what I might choose for race wheels. This fits very nicely inside of that price window you all indicate is your sweet spot.
There is one thing more I'd like to mention about these new IA models. The stem is designed to integrate with the frame. I'll be writing more about tri bike stems in the coming days, but Felt is the one company making a mortal version of a superbike with a stem congruent with the frame.
How does the PRfive compete with this? It starts out at $3,700 for the Ultegra package, which means it comes with Ultegra derailleurs. But it doesn't have Ultegra brake calipers, it's got Shimano 105 calipers but they're pretty nice. It's a shame to pull off the front to replace it with the TriRig, but it'll have to go. The aerobars are first-rate Profile T4 but the extensions I'll replace with carbon T3s. It's got an ISM saddle so there's a fighting chance this is what I'll end up with, i.e., no upgrade needed.