[Kuritza]

I disagree that Bogarus calls for a sloth scale.

Heavy cavalry, Malaia Druzhina, is ok. Just 5 gold more expensive than Chelms knight, with slightly lower head protection and strength but with 50% cold resistance which may come handy time after time. Its your only real troop, and its rather resource heavy.
Infantry is not stellar, but at least its pretty. City guards even have an above-average morale. If you want to see a really crappy infantry - check caelum, these flying retards dont even qualify as a meat shield because they rout so fast. Bogarus has a decent meat shield to back up its mages.
As for archers - precision 8 is crap, I agree. But these guys are cheap! In great numbers, precison doesnt matter as much. Also, Bogarus has got access to both wind guide and flaming arrows, and thats worth something. I have a feeling that Bogarus archers may be made a force to be reckoned with.

All in all, I'd say that Bogarus armies are rather weak if you compare them to favourites like midgard, mictlan etc, but not bad enough as to justify sloth 3. You wont go far with no troops at all; besides, production scale allows you to produce your units en masse when you really need them instead of recruiting a couple of them each turn, thus paying less upkeep.
Oh, and if you're so affraid of rain of stones, get yourself arrow fend.