Ah, yes. With FACs, Bremen's bit works well. Though honestly, I don't use them as anything but system defence forces (read: crap to station in-system to keep the civilians from bitching when fleet detachments are deployed). They're too small to absorb much fire, but are much more costly than fighters, given that the only way to make them effective is to deploy them in the dozens. At least against missile-armed opponents that aren't at a severe tech/numbers disadvantage.
They might have a purpose as semi-disposable and/or long range missile platforms. You don't need to absorb fire if you can outrange and outspeed your enemies, and if do get hit, it's not like they are really all that costly. A bit of light armor if you have decent tech on that area, and you can have each FAC absorbing at least 2 to 3 shots, maybe even a couple more.
That's the thing, though; fighters already act as missile platforms, and you can build a dozen fighters with twin box launchers a lot cheaper than, say, 4 FACs with 6 launchers. The main thing is that if you use FACs to any serious degree, you have to pretty much dedicate a shipyard to fulltime production to get them in useful numbers, and their destructability tends to result in high mineral waste. Fighters will by and large survive entering enemy missile range (mainly because they're too small to detect at anything but very short range), are cheaper, and can be produced with (fighter) factories rather than shipyards. If you're going to bother giving FACs enough armor to take multiple hits, as well as the engines and fuel to outrun and outrange actual warships, you're probably better off just going ahead and making them into frigates or corvettes. I've pretty much given up on FACs entirely in favor of frigate battlegroups with dedicated PD and LRAS ships, as they tend to be hefty enough to only lose one or two for each enemy cap ship killed, while still being nearly as cheap to produce as FACs.
The one thing I still occasionally use FACs for is as planet-based SDFs; they're going to get chewed up regardless of what you do, but they can buy time with their deaths. Ironically enough, you can get a pretty good idea of FAC tactics from David Weber's work, and it's pretty much the same thing: either use them as disposable system defence, or mass them in absurd numbers.
But eh, to each their own. Also, be careful to not let the damned officer autoassignment put all your admirals on FACs, as it seems to love putting your most senior officers on the shittiest, oldest ships still on active duty.