I started the reseal on a 135 gallon tank I had here. This tank did hold water for a month. The old silicone on the corners had peeled back, and had green gunk behind them, etc. It took about 3 hours of scraping, 10 razor scraper blades, and a big portion of a 12 pack of bud light. Just got done wiping the seams with acetone, and have some touch up scraping to do.
I noticed that the inside seam seals are secondary seals compared to between the panes of glass. My theory that if the tank isn't leaking, but you have funky vertical silicone in the corners, this is a pretty simple repair. If you have a leak between the big pieces of glass, it looks like the only true repair would be to separate the big glass seams and redo them totally. Maybe if the leak is towards the top, you could get by with just doing the inside silicone, but down low there would be a lot of water pressure, and a potential for a huge leak.
Overall not a bad deal so far. I can see once you silicone the seams, getting it done quickly and getting the tape pulled back before the silicone starts to skin may be a big issue. A tank this small, one guy running the silicone gun, the other guy smoothing the silicone, and then the first guy pulling tape after getting done putting silicone down seems like a good idea.