K2,
I have two rent house pools and my pool. The two rent house pools have non-operating main drains that are plumbed into the skimmer. My main drains are plumbed back to the equipment pad through a Jandy valve.
The two rent houses have single main drains, with raised (VGB) covers, even though the drains don't work.. I have double main drains with VGB covers.
I take care of all three pools and I can't tell of any difference in how they operate.
In my mind, the safety factor of not having a main drain is waaay over blown. It is absolutely true that single main drains with flat covers are a hazard.. But main single drains with VGB covers and dual main drains, are very safe. Nothing is perfect of course, but it would take a lot of effort for someone to get stuck on them.
I can't see enough of an advantage of having a main drain to go to the expense of upgrading the two rent house pools so that that current main drains work.
If I were to build another new gunite pool, I would install main drains because it does give you the option to run the pool with the Skimmers shut off. I fully admit this is not something that I normally do, but since the cost of having a main drain is so little, I can't see not having it installed. I also have a vacuum port in the sidewall of my pool that I have yet to use. Again, the cost to add it was next to nothing and it gives me that option if I should ever need it. (I have Robots)...
I would never add a main drain to a liner pool...
I guess my point is... Main drains or not, I doubt you will really notice the difference, but you should make the decision based on facts and not on scare tactics..
Thanks,
Jim R.