I was wondering if people had any opinions.
I am a big of the virtual connect modules and have only used the pass through's when the blades weren't virtualized and were running large Datbase Servers.
I'm not a fan of VC on its own, it gets expensive and isn't as flexible as you'd think - BUT in conjunction with the Flex-10-based blades (495, 490, 460 etc) they're fantastic. You can effectively cable once and never go back to the rack, everything is just a mouse-click away. The performance is great and even our network & SAN guys don't get sniffy because they're not technically switches (though there's a whole discussion to be had with that one). For organisations that are very change-averse they're a godsend, no more sending staff to site in the middle of the night to repatch a server from one zone to another. One thing to be aware of is that you'll need to keep your firmware up to date, oh and VC Enterprise Manager is a bit expensive for what you get if you ask me.
So to sum up, passthroughs work and are ok if you can breeze into your data center any time you like to make changes as they're needed but VC is wonderful if you have the budget.
We are testing the virtual connect modules and are loving them. Pass through's are good if you need to keep physical security but cost more in switch ports and management overhead.