Nice - the only thing I'd do differently would be to use nohup with this line:
nice -n +19 testScript.sh &
That'll ensure that even if you log out it carries on running.
I'd also potentially redirect stdout / stderr to files so you can see what's going on without losing the output on the terminal.
./nohup nice -n +19 testScript.sh >stdout.out 2>stderr.out
Then you can just do the usual "tail -f" on stdout.out and stderr.out to see what the contents are.
It depends on how long it takes to execute though - if we're talking about queries that take a few minutes and you'll always stay logged in, there might not be a huge amount of point. If we're talking about queries that span multiple servers and are so big they could take hours or days, I'd definitely recommend it.