Fold or push?

Can I rep the flush?

PokerStars Game #14479399502: Tournament #73440310, $4.00+$0.40 Hold'em No Limit - Level VI (100/200) - 2008/01/11 - 11:50:07 (ET)
Table '73440310 18' 9-max Seat #9 is the button
Seat 1: janosb78 (21234 in chips)
Seat 2: EE Meister (8240 in chips)
Seat 3: ging44 (6362 in chips)
Seat 4: Silense (4248 in chips)
Seat 5: bigtoe821 (1729 in chips)
Seat 6: Mantheman (19770 in chips)
Seat 7: G8keepr (5230 in chips)
Seat 8: Dagger71 (20195 in chips)
Seat 9: rockwell0610 (5258 in chips)
janosb78: posts small blind 100
EE Meister: posts big blind 200
*** HOLE CARDS ***
Dealt to Mantheman [Kc Js]
ging44: folds
Silense: folds
bigtoe821: folds
Mantheman: raises 400 to 600
G8keepr: folds
Dagger71: calls 600
rockwell0610: folds
janosb78: folds
EE Meister: folds
*** FLOP *** [Th 7d Qd]
Mantheman: bets 800
Dagger71: raises 800 to 1600
Mantheman: calls 800
*** TURN *** [Th 7d Qd] [5d]
Mantheman: checks
Dagger71: bets 1200
Mantheman: ???

By my calculations there is 4700 in the pot, and at this point you know your opponent almost certainly has something decent. It's a coin toss as to if you should go for the straight or not, but I'd be inclined to fold here since opponent might have a flush against you already and 2 of the six cards that will make your straigh will also be a diamond.

This looks like a 180-man game to me, this forum is probably best for everything up to and including 45-man tourneys, if you want me to move it to the MTT forum you might get a better answer.

His hand is screaming strength to me. Readless I find it hard to believe he'll fold to the chance you have the flush.