I usually late register in MTTs just because I don't think that playing at the start when blinds are low really gives me an advantage over any of the other players. Also, I play very nitty at the start, so more often then not, I'm folding a lot of hands and maybe winning a few small pots here and there. Once in a blue moon, I might pick up a ton of chips early, but what usually ends up happening is I'm below average stack by the time blinds get to 50/100+.
So, if starting stack is 5K, by the time blinds get to 50/100 or higher, I might be sitting on a 3.5K or 4K stack. Where, if I had late registered, I can start with a 5K stack at 50/100 or higher blinds.
To add, starting with blinds higher and fewer starting BBs makes playing a little bit easier as I'm probably folding a lot of small pairs early, and playing my big pairs and big hands very aggressively in mid-late position. Also, a lot of players at the micro-stakes tend to play very passively around the mid-stages and/or they over value small pairs and weak hands. So, it's easy to pick up pots and double off of them in the mid-late stages.
I don't think I'm giving much up not playing the early stages because I feel my mid-late stage game play is good enough where I can enter an MTT late with 25+ BBs and still do well.