I replaced 2 lifetime 1 TB TiVo HDs this spring after waiting for the software update to roll out. You are still able to get over $300 (I got 380 and 330) on eBay for HD lifetimes.
Pros: HD interface, glow remote (I also got a slide remote but find it is not used that often...), iPad app, and an A+++ for multiroom viewing (pause in one room resume in another), stream option for viewing if you don't want to transfer, and deleting remotely. I'm in southern NH and hoping I am in the "Boston area" for the Comcast OD rollout. Also looking forward to the Stream and IP box.
Well worth the upgrade IMO. We really love the new units. If you have the cash I would get the XL4 as it seems to be getting abilities not available to the base units.
1 Premiere Elite, Lifetime Sub
1 Premiere, 2TB DVR Dude HD, Lifetime Sub
Comcast Digital Cable, XFinity On Demand
Wired Network Connections