Sounds like you were at the Evergreen Quilt Show
I personally just bought an Advante from the dealer you spoke with at the show. I've had my machine for 3 weeks and LOVE it. The dealer will teach you everything you need to know to operate the machine properly and adjust any tension issues. As others stated above, there will be some learning curve to the actual quilting design part, but I look at that as you just need to practive. The dealer offers all kinds of classes and even will do customized training based on what you want. You don't even need to have one of their machines to take their classes.
I personally got the 12 foot table since I build the room to fit that size frame. I have quilted 2 quilts on the machine so far - both were entered into the show and I was able to get a 3rd place ribbon. So I have not had any tension issues. That being said, the dealer does teach you how to adjust and what to check before you start quilting to ensure you have even stitches.
Feel free to private message me if you want to know more about my experience. Good luck making the decision.