The entire purpose of the RFB was to get a 32" barrel .308 into the smallest overall length package, in this case a mere 40" in OAL.
The "target" model with it's barrel of 32" can fire a very heavy .308 win 7.62 NATO bullet of +200 grains at over 2500fps, giving it a muzzle energy and sectional density superior to .300 Win mag out of other rifles with shorter barrels and longer OAL's. The ballistics with a 210gr .308 and a 32" barrel (which would be a joke in a bolt-action, AR, HK, or M-14 action) are even within spitting distance of the low-end of .338 Lapua mag. ballistics. When you plug the numbers into one of the free on-line ballistics calculators, the super-heavy .308 combined with the monster 32" barrel getting an extra 10-15% in fps, has something like more than 50% more retained energy at 1000 yards, and will also buck cross-wind much more than 50% better, because the heavy .308 will have both velocity (time exposure to cross wind at a given wind velocity/vector) and extra mass to create lateral inertia to fight that cross-wind too.
So in essence, Kelgren or whoever at KT who came up with the idea of the RFB, they took the one advantage of the bullpup design, the savings in OAL, and gave it ALL back to the barrel length to eek every last ounce of ballistic potential out of the .308. And other deficits bullpups have, like the high-bore axis of scopes that bullpups have shrinks to become meaningless when you're playing at over 500 yards, and have a high quality scope that has a massive amount of vertical deflection to take advantage of extreme range. The bullpup's mag-change done practically in your armpit is awkward, especially as compared to the AR-15/AR-10 family, but it's still light-years ahead of many of the bolt-actions that are still in wide use...
That is the "point" of the RFB.
The sporter and carbine variants, of which I'm sure will comprise 90%+ of Kel-Tec's sales are to make them sale-able to a wider audience so the investment in tooling and R&D at least have a chance to pay off for Kel-Tec.
I'm still hoping that they come out with a production version of the .223 bullpup the "Sub-16", at more Kel-Tec'ish prices that was the initial inspiration for the RFB…
http://world.guns.ru/sniper/sn75-e.htm