glad you're getting a new one
why did it blow up? what did the engine builder say? 2 hrs i'm assuming at idle in the shop shouldn't grenade like that. i'm not an engine genius, but it must have been fubared.
do you honestly trust them to rebuild you another 23k motor if it blew up that easy/fast? what trust can you possibly have that the shop will build a second motor better? is there guarantee that whatever blew it the first time won't happen again?
i'd ask for a full refund and swap a 4l back in....... for that much money, the damn motor should change its own frawken oil.........