Dont recommend you exp off these till 69. Good for 69-71. They have pretty good evasion so anything lower will have tough time hitting. Level range is similar to catolepea(sp). Slightly harder for nin to tank imo, because these double attack very frequently, ripping through shadows much faster then dhamels do.
Partied extensively on these with the following party setup.
67NIN 67RDM 67WAR 68RDM 68SMN 69THF
Got well over 4k/hr running these w/ the occaisional physician and tartarus eft.
High eva as said would generally take 2 SC's to take down. But chained well over 200 on Chain 1+ and with stoneskin were actually much less bomb killing than the fascinators, venerers, alastors XP'd on a few lvls earlier.
I wouldn't advise xping off THESE gobs, at 66 they were so evasive that the sam i was with, who was clas in a haubergeon and two snipers rings didn't even hit more then me...and I BELIEVE it was IT high evasion. So im going to guess it was a 70+ mob easy.