i have gotten 2 in the last few months and they both work on 4s, it has a built in lvc for 4s, you just need to disable the bec, and use a ubec or a rx pack
All of the mm's have had a 3s rating, and all of them have been able to work on 4s when using an external bec or rx pack (4s is out of warranty on all of them). Some of the old ones would work on 5s and I think up to 16 cells nimh. The new ones don't work on 14 cells or 5s.
Sorry, but I don't know how to tell between the old and new ones by looking at them.
Highflier
I have a brand new one from Bishop Power Products.
On the side it says "3S LiPo / 14 cells NiMH".
I use it with 5S2P A123 which is 17 volts or so, and it is fine if you power it up AFTER the UBEC. Otherwise it beeps overvoltage.
It gets hot but hasn't thermalled yet.
I hope this helps
That is where mine came from coming from. It just got here, But you never know with the way some of the shops handle inventory. Good thing is sounds like 4s A123 is a definit go on these controllers eitherway. (Bec Assumed)