If u already have several 30rd Pmags. The extra 10rds plus the extra $27 just isntnt worth the upgrade.

Now if u had a few 30rd mags and u could order as many 40rd mags as u wanted. Then "maybe" it would be worth the upgrade. ut until we see them get down to the $13-$15 range (shipped). Then i highly doubt u will see a huge demand for them.