I had this setup to start, and quickly came to despise the 9" harp and the bobbin - would be changing bobbins sometimes twice in one pass. Moved up to the Pfaff 18.8 and now am a happy camper. The bigger Pfaff also has the bigger bobbin and the bigger harp.
There are some good research resources for longarms - including http://www.longarmuniversity.com/ . There are often demos at shows. If there are some la's near you, chat them up and ask what they do and don't like about their machines. Being able to do some real hands-on work on candidates will really help your decision.