Bingo, I always test any transit that I am unsure of. I have had 12 years experience in construction, mostly laying pipe, and pulling stuff back out of the ground and putting it in right again really stinks, so taking the time to check it out is definately worth it.

I have a transit myself, and even though I don't use it much, I always check it out first. My first pool I used the transit, and the second one I used a rotating laser level with a reciever. The laser is way better, it beeps at you when you get it right, my second time around is perfect, while the first time around was within an inch.

I am probably what you would call an extreme perfectionist, and I made sure it was also perfectly round, the bottom was immaculate, I used a four foot asphalt rake to get the bottom smooth. If you go over it using the rake in two directions and watch the gaps under the rake, you can fill in your voids in the sand. And I then made sure that all of the supports were perfectly plumb before I finished putting on the top rail.

All in all, you should not be too carefull in my opinion. People will be more amazed that you did it yourself if it is done right. And a big plus is finding this forum, now I can say that I cut the upkeep cost to a tenth of the original method.