I looked at the deco when I was in the market for an embroidery machine. Actually I looked at just about everything! LOL I ended up buying the PE770. Bernina machines require exclusive software when you are ready to digitize your own designs/pictures. Brother uses the software the nearly everybody else uses, and there are a lot of companies that write software for it. I agree with you about the price difference. I used it to buy thread, stabilizer, etc. I don't have a local Brother dealer so I bought mine from Amazon and got what I believe is a good price. Also, because the Brother is a twin to the Baby lock (baby lock doesn't make an embroidery only machine), I can get support from my local Baby lock dealer. I am very happy with my PE770.
I'm sure Bernina owners will tell you how great their machines are. You really should try them out and weigh the differences in your own mind to decide which is best for you.