Well no idea about this 'overpowered' crap. I have 'solo'd' a rat spawn, with my new improved pet, which is great! However, having said that it did take me 1.5 HOURS to do it which on siege is a bit dodgy at the best of times. Pretty sure a sampire can do it in about 15 to 20 mins. So who is overpowered?
And yeah I have tested all manner of pets on this particular fight on the test centre at the Ilsh spawn or despise and the fastest I can solo it is about an hour and 20. Maybe there is a pet that can solo it better that I haven't tested yet but so far I have tested lesser hiryu, najassaurus, giant beetles, tzuki wolfs, cu's of various build, serpentine dragon and nightmare. Not counting the old greater dragons etc.