Flat calling 3-bet with KK, right play? Stars 4/180

[Wish]

I'd usually try to isolate here, but I thought that flat calling would invite UTG+1 to try to iso instead, which I would happily call with a huge hand. Obviously, that much of the plan worked (I won't post the results), but was it the right play? Could some of you with some experience with PokerStove or similar programs figure out how much my equity is hurt by allowing UTG+1 to come along? I'm thinking it's got to be significantly +EV to get as much money in the pot as possible here, even though it increases my risk of being drawn out on. Also, in your experience, is this play too transparent against better fields than I might expect to find in a 4/180?

POKERSTARS TOURNAMENT #64306895, $4.00+$0.40/180 HOLD'EM NO LIMIT - LEVEL III (25/50) (manually converted)

MP1 (3455 in chips)
MP2 (757 in chips)
Hero (4195 in chips)
Button (1445 in chips)
SB (2930 in chips)
BB (1645 in chips)
UTG (1805 in chips)
UTG+1 (2665 in chips)

*** HOLE CARDS ***

Dealt to Wish2007 K[img]/images/graemlins/heart.gif[/img] K[img]/images/graemlins/diamond.gif[/img]

1 fold , UTG+1 raises to 250, 1 fold, MP2 raises 757 (all-in), Hero calls 757, 3 folds, UTG+1 raises 2665 (all-in), Hero calls 1908