I've been running a lot of prints over the past few days with the new heatbed, but the old electronics (Arduino/RAMPS), and the heatbed transistor died a gruesome death. Very weird, too as, it can be basically turned on once after power-on, and then it stays on, with no regulation.
Alas, it is an STP55N, and seemingly the v2.0 heatbed was too much for it. The RAMPS board has no heatsink for the FETs, which is a major problem with the STP55N, as it's not quite fully open at 5V, so sinks a significant amount of power.
I replaced it with an IRF3808. In theory, that transistor is better suited for this setup. The STP55N is rated at 15A for a 5V gate voltage, which is with a heatsink, so without a heatsink it can't really sustain the 10A without overheating. The IRF3808 has much better specs, so it should drive the heatbed without a sweat. We'll see how it does in the long run.
Long story short, if you run the new heatbed with the RAMPS board, I highly recommend replacing the heatbed transistor with a better one.
Watch out for the RAMPS Heatbed Transistor!
Even with the old resistor heated bed it became way to hot for my liking. A wet finger made a sizzling sound. I've attached a piece of metal to it:

Stay's cool this way.
Now I'm using the new heatbed, and so far no problems. I just started a ABS print with a 75 degrees heatbed. Lets see if it survives
If you attach a heat sink yourself: Make sure the metal parts do not touch the other mosfets! If you do the correspondent attach device to that mosfet will activate.

Stay's cool this way.
Now I'm using the new heatbed, and so far no problems. I just started a ABS print with a 75 degrees heatbed. Lets see if it survives

If you attach a heat sink yourself: Make sure the metal parts do not touch the other mosfets! If you do the correspondent attach device to that mosfet will activate.
My Felix 1.5 printed designs on Thingiverse
E3D V6 Hot end upgrade for your Felix
Tweezer bracket for your Felix
Led bar upgrade for your Felix
E3D V6 Hot end upgrade for your Felix
Tweezer bracket for your Felix
Led bar upgrade for your Felix
Attaching a heatsink is almost futile, due to the way the transistor is placed on the board. Not for the faint of heart, as you have to take good care the heatsink doesn't touch any other metal parts. I decided against it when I got the printer, as I figured I'd just short it to something important at an inopportune moment.