SirTopamHat:
I'm not sure whether you are asking a genuine question or taking the p*ss, however, here are my thoughts.
During my walkround, I very carefully make sure that the gear pins have been removed. I also check that all of the gear pins are physically present in the box provided on the wall just behind my left shoulder.
(You should note that the pin showed to the flight deck by the ground crew (pushback team) is a separate nose gear pin used for pushback purposes).
Now then, we taxi out and get airborne and the PNF announces "PRGU" and you ask for the gear to be raised. Not a lot happens!
By the time the realisation that either you have a serious gear problem or that the pins have been left in has sunk in and, assuming that all else is well (no engines have failed etc etc) then the aircraft would probably be going past 2,000 feet.
From 2,000 feet Jet A1 will not reach the ground. You are not going to go anywhere very far. (I have done several gear-down ferry flights and the fuel burn DOUBLES).
You are way over the top for max landing weight and you are not in good shape performance wise. Can you give me any good reason as to why you shouldn't dump apart from the loss of face which is going to come anyway?