I've had a quick look at Trunk Networks (and Leetline which is their gaming sister offering). They seem a little more expensive, in the IDnet ball park for pricing, but I guess for a smaller company this is to be expected.
I guess the only thing for me now is to do try and get a bit more info on Trunk Networks and try and compare that to Zen. From my brief searches, there are a few reviews for Trunk Networks/Leetline but this isn't much to go on, especially when locking in for a 24 month contract.