Bought a Kenmore in 1971. Still use it. Never been to a shop, I can easily clean and oil myself because the were designed that way. Bought a Viking Sapphire 870 in 2008 - all the bells and whistles. Been to the shop several times and very inconsistent when trying to FMQ. So much for upgrades.
I bought a Brother 1500s two years ago (straight stitch) because I could not get a quilting foot to fit my this particular model of Kenmore. Like the Kenmore it is not computerized and I can clean and oil it myself. Quilts beautifully. So now I use my Brother most of the time, and my Viking only when I need fancy stitches. Kenmore has moved to a cabin in the woods, still love it and use it, and it would be my go-to machine if I could quilt with it.
Bottom line, be wary of upgrades. Be wary of bells and whistles if you don't want to spend a lot on shop visits. Most of the new machines are designed so you cannot maintain them yourself.