Welcome to the board! I'm sorry I don't have any direct experience with the Janome but I looked at the model. I was lucky enough to have use of a long arm for several years and got spoiled and really prefer them.

I was given a modern Bernina 820, which I think is similar and I can tell you the large throat does make a huge difference over my old sturdy vintage workhorse. For the quilting part the BSR (bernina stitch regulator) and/or the built in walking foot help quite a bit and I like having the automatic Serpentine Stitch for quick quilting down. I still don't want to wrestle a queen sized quilt through my machine, but I could and do the level of detail I would want to do. I'm pretty happy working up to a twin size.