I am wondering if the reason you are looking at this particular machine is because the dealer is nearby.
Personally, I would want to compare several different brands of sitdown machines before making a purchase this large. I would especially be interested in the Innova 18" sitdown (no longer has stitch regulator sitting on machine; now hidden), the Sweet 16 from Handi Quilter, and the George from APQS. All of these brands have great track records and you can probably find quite a few personal reviews of them online. I couldn't find many reviews of the Babylock Tiara, probably because it has not been around as long and/or is not as popular for a sitdown machine. My biggest concern about the Babylock is probably with the complexity of the machine and possible tension issues, which I did see mentioned in more than one place online. Found this Youtube video that might help (be sure to read comments too):
https://www.youtube.com/watch?v=2DBR8xcku5I
Personally, I would prefer to have one machine for piecing and another for quilting. Plus, isn't the harp size of the Crescendo substantially less than that of the Tiara and the other sitdowns? Larger harp size really helps when quilting, especially if you get one of the quilt suspension systems (such as Jenoop). You have to decide if the additional features of the Crescendo would make up for the more limiting harp size.