I went to the T-Mobilestore the other day and played with a Nexus 4 and just after a few minutes of playing with it I wanted to retire my VZW Galaxy Nexus.. The speed on T-Mobile's network was pretty fast. The device has a high build quality which felt much nicer in my hand that the Nexus. I love my GNexus, but am ready to replace it.
I don't care about bandwidth, HSPA and LTE both have bandwidth. It's the lower latency that LTE brings which is why I want it. However the OS, APs, hardware, etc aren't fast enough to take advantage of the lower latency that LTE brings I feel.
With my last statement being key in my mind, the Nexus 4 is a very attractive offering. The battery usage would be way less since only one radio would be used compared to the GNex. I'd probably do the Nexus 4 off contract and bring to a provider of my choice.
I sure hope Google keeps up these low cost high end phones to change the cellular market. The Nexus One off contract was before the right time to pull off BYOD, I think this business model can work now.