Decent QinQ endpoints?

So we've got a ton of Dot1Q VLANs that should have been QinQ stretched all over the place, and we're looking to clean it up.

Unfortunately the switches we have in place (dell Force10) don't have any provision for any complex topologies. They call QinQ "vlan-stack", with "vlan-stack access" being a port that takes Dot1Q tagged frames (C-Tags), wraps it in an S-Tag and forwards it along. The problem is that there can only be ONE S-VLAN on a given vlan-stack access port and there's no way to natively support topologies where some C-Tags get a certain S-Tag, while some other C-Tags get a different S-Tag.

So one option is to keep the customer facing port straight Dot1Q and use another pair of ports to loop some of them onto a given S-VLAN (burning 1 pair of ports on the switch per S-VLAN), and requiring every customer VLAN to be explicitly configured on the switch, etc. It works, but it's a nasty kludge.

A coworker suggested using Accedian NIDs for this purpose. The way he tells it we can just slap these things in-line and configure arbitrary tagging/untagging behavior. Pretty much what we're looking for. Issue is he's never used them for that purpose, no one else on our team is remotely familiar, and we also don't have any to quickly test.

Can anyone share some perspective on using them (or some other equivalent) devices for this purpose? Gotchas, etc?

He's got the task of "find someone we can buy this crap from", but if you've got recommendations for suppliers (we're thinking MetroNIDs for 1G, MetroNODEs for 10G), or a guess at how hard they're going to be to source, we'd happily take that as well.