O, I didn't see that there was another cold caller. I would also call preflop. Your implieds are bigger. It's hard to stack a good player out of position when you have a set and he has overpair. In a 3 way hand, the pot will be bigger so the pot will get full fast, so it's good. Also you might have the luxury to get set over set against the cold caller.
Also you are deep, didn't see this either
(I must pay more attention to the the details from the start).
Let's see this from an mathematical point of view, you have to pay $3,75 to see the flop. You hope to spike a set. If you do you have to get at least 1/10 postflop to be +EV on the long term, so you have to win at least $32 more (because the pot already has +$5.5 from CO). If you think you can achieve that than it's profitable.
The minus is that you're out of position and your hand strength it's revealed if you c/r F or donk Turn.
If you get the set and MP3 has KK,AA than we can speculate that he will bet 2/3 of the pot, around $13. If CO calls you need only 6 more dollars (13+13+6=32)to make profit long term. That will be easy, 6 dollars are bound to enter the pot in next streets.
What happens if CO doesn't call? You will have to get $19 more. Now it depends on the board.
If it's draw heavy, you can just call the Flop and check again if the draws don't hit on the turn, he will absolutely bet again to protect. If the draw hits... I don't really know what to do, to a donk he will probably fold, to a check he will probably check behind, that a risk you must take if your going with this line. But if the Flop is draw heavy, than a C/R would not look so bad on the Flop.
If it's a dry board, a check raise will surely scare the opponent. A check/call seems ok, but what next...?
It's hard to get the value you want out of position.
PS: I write all this for me as well as for the author. Verbalizing my knowledge. And also learning new stuff.
I hate playing out of position so I'm always in search for new ways of getting better at it.