Thanks bunches guys! I already got it!!! I started a thread on the "build" over here:
I know the consensus was leaning towards the MK6, but for the price I paid for it, I am pretty happy and already put in an offer for another one. Your explanations of the differences REALLY helped me decide too.
I think the MK5 will work just as well for my needs as the MK6 would, and at a MUCH MUCH lower price. That savings will let me put more money into these where I want to spend it. Like banging in 16gb memory.
MILDLY annoyed though. The listing claimed a battery and power adapter were included. They weren't. Neither was the HDD caddy (but that was expected). Not a deal breaker, but hey, the listing says what it says.
Still as we likely all know, the generic power adapters are a VERY BAD IDEA. If you don't know, they are much more poorly built and arc when connected to the power plug. I went through 2 plug jacks and power bricks before getting a genuine Panny one. The IBM adapters are safe too. Since using those, haven't lost a single jack.
Not sure who suggested this, but one of the long timers over at NBR suggested an inline switch. I ordered a couple then and that has also helped. I have almost worn one out already.