[c-nsp] Any gotchas in upgrading ASA5520 pairs?

[Scott Granados]

Hi,
    I have two ASA 5520 devices in a active standby pair.  I'm presently at 
firmware 7.0.7 and ASDM 5.0 and want to upgrade to 7.2.4-33.  I've googled 
and found some detailed instructions and the process seems simple and 
standard, upload the image, change the boot vars, save and restart.  Is this 
correct?  Would the following work?
First, upgrade the standby, restart, once back up fail over to standby so 
the primary becomes standby and repeat?  Are there any issues with 
mismatched images that I will need to be concerned with while the two 
devices are in transition?  How about any gotchas from the upgrade of 7.0.7 
to 7.2.4 itself anything I need to know?  I didn't see any alerts in the 
directions but figured I should check here.  Any pointers would be 
appreciated.

Thank you
Scott