My guild recently downsized to 10 man after facing major issues as a 25 man guild. We managed to down 3/7 as a 25 man guild and only two raid-days after downsizing we had 6/7 Heroic. We went in last Wednesday after the Beth'tilac HC nerfs and LITERALLY 2-shot her. I don't know how big of a nerf she was dealt but it was insanely easy for us, so I'd say go Beth'tilac if you have a hunter available (completely trivializes the spiderling/soaking part of the fight).
As for Baleroc it is also extremely easy if you have a shadowpriest and a decent healer-setup.
You'll face succes regardless of which boss you decide to pull - they are both jokes imo.