Hi Doug,
I went through the same thing you're going through a little over a year ago. Let me start by saying I ended up buying the Shopbot BT48 Buddy.
I, also, started out looking at the Shark Pro. I saw it on Rockler's website and then went to see it personally at one of their stores. It's a nice little machine for a small hobbiest. I thought about it for several weeks and finally asked the store manager for a demonstration before I spend that kind of money. Not a single person in the store could operate the machine.
Now, it's not like I can go down to the store and see a Shopbot demo either though. But, it really made me wonder what kind of support I might be able to expect when I ran into problems (and you WILL run into problems).
So, I expanded my horizons and started looking at other CNCs available. I came across the Shopbot site and read up on their machines for almost an entire day before I even made my way to the forum. I'm not a machinest and I was adequately confused by all of the information I had just inhaled. Somehow, it all started to make some sence once I started spending a little bit of time lurking on the Shopbot forum. A lot of the questions I had were easily answered right here. I had to do some searching for some of the answers. But, they were here for me.
I was even lucky enough to have a Shopbot Camp scheduled about a hour from my house during my quest. Bill (Doc) Palumbo encouraged me to attend the camp. I got to see the Shopbot actually run some parts and I learned more than I was ready to learn about all kinds of topics related to the Shopbot and the software.
I left the camp almost certain that I'd end up with a Shopbot. But, I continued to do my due diligence and shopped around for several more weeks after that yet. I had called Shopbot and asked so many stupid questions. I'm sure they don't remember, but I sure do. The staff at Shopbot was great. But, the guys here on this forum were without a doubt the determining factor when I finally made up my mind and ordered the Shopbot. There are so many talented folks here, and they're almost all willing to share their knowledge to help you out whenever the time may come (and it WILL come). I know that the Shark guys have a forum. It's no comparison to this forum and these guys.
The software comparison doesn't exist. V-Carve Pro and Partworks are the same thing. Partworks was made for Shopbot to speak the Shopbot language. Same-O Same-O.
Spend a few extra bucks and get the machine and the support group you're going to need. You won't be sorry.
Eric Erickson
Shopbot BT48 Buddy