Just to get back to the threads question. I like the sslyth lhamaean HQ idea. The HQ suck in the DA codex atm is, Mr. no ap 2 weapon or miss no armor against shooting both needs upgrades to kill something and survive and then we left with doctor evil who is not great in cc or in defence. All are expensive if you want to kit them out.
The grotesques is best if they are the coven ones so not HQ if you are going a normal DA build. Taking them from the DA codex feels a bit like a self nerf. The grot bomb is not immortal so any that helps your 300+ unit is something you want.
175 points of poison shooting "death" that is tough as HQ. Looks like cheap and good HQ to me. If you get a flamer or instant death guy as HQ doesn't really matter much.