If you want to execute multiple MSRs in parallel you might use the Queue Table approach I described here:
Insert/Select the MSRs into the Queue Table and then run as many SPs in parallel as you want (just take care that there's only one MSR per table).
Interesting, I might try to code both approach (shell script with & and the queue tables).
I never had the chance to use queue tables so it can be a good experiment.
Thanks guys, it has been really helpful !