While demoing my Cupcake CNC bot a while back, the extruder succumbed to plastic build up at the interface of the PTFE and the heater barrel. Not soon after I tore the extruder hot end apart Makerbot Industries released the second version of the heated build platform, and later teh MK5 hot end. I snatched up both upgrades but haven't had time to retrofit my bot until last weekend. After some rewiring, soldering, moving and remounting of various electronics, and some assembly of various mechanical bits, I had a working Makerbot once again!
I was surprised that the first print actually finished up fine. OK, I did help it along a bit by raising the Z axis a bit while building because it was putting out way too much plastic, but it did finish a 1 hour print successfully on the first attempt. I've been using a Paxtruder design for a while, so I've got a good idea of how to tune the filament pressure, which probably helped a bit as well. I'm loving the new hot end so far. I've been able to speed up my feed rate by %30 without running into any issues, and I've had good luck going raftless for the most part. These two things combined have halved the print times of some of my prints, which is awesome. I'm still tuning things but my initial impressions are very favorable, and it looks like the new setup will be considerably more reliable.
On a side note, one tool I found useful for dealing with the heated build platform is my Cricut