I was thinking about this thread. I just got a lot of live sand from a fellow reefer. What I did was place it in my quarantine tub with heat and a pump.
I was thinking of letting it stay in there a couple of weeks. I figured there would be no harm in that.
I used to dump everything into my tank. However, at this point, almost everything goes into the tub. (I do wish I could say everything, but that's not the case).
However, for your application, since there is no wait time and your just transferring from one tank to another, it seems like a fine idea.
I am thinking that what you could have done was put your current live stock in a holding tub and then dump the live sand in the tank and wait until everything clears up.
Again, I don't see a big deal in just dumping it in. I myself, have dumped live sand from mail order straight in the tank, and it cleared up right away. Just thinking about the sand storm and maybe the corals may not like it.
PS. Just food for thought. I don't like this idea I am just giving a tidbit. At Country Critters they vacuum all their sand into a strainer and clean it out on a regular basis. To me, that's just killing all of the live stuff, so I don't do that.