I have read here several very different opnions but I can agree with who told that this strategy of doing L Reg or not depends on the following aspects:
1) Structure of the MTT (Turbo or Normal, Deep or Low Stack, Duration of the LReg, etc);
2) Your intention (if just finishing ITM or if achieving the FT and top positions by the end);
3) Strategy and Way (tight or loose agressive) that you normally play;
Because if you enter in the end in a MTT with 2 hours of L Reg and it has a TURBO structure with a low innitial stack and if you do the late registration only by the right end of registration period so you will have a stack much below than the average stack of the tournament but relatively close to the position to finisish ITM and taking so much time to finish ITM...
In this case it will be very hard to finish in a top position with a stack much shorter than the average and compared with the players in the top and you will depend a lot of Lucky (variation) in several
hands to grow your stack to reach top positions but if you have at least some lucky and choose some good spots to go all-in and double your stack at least 1 or 2 times you can finish ITM much easily and faster than entering in the beginning...