The only problem I see is the size of the panto's. With any of the 9" machines like the Brother 1500, Janome 1600, Juki TL, Babylock Quilters Choice Pro, Viking Mega Quilter, Pfaff Grand Hobby Quilter (& probably several others I've forgotten)--you are going to be limited to a 4--maybe a 5" panto if you're really good about tightening the quilt on the takeup roller and stop in the middle and turn the quilt around or you're only doing small baby-size quilts. Another idea is to adapt the larger panto's into top half/bottom half designs and then just practice, practice, practice to get them to meet in the middle. Where there's a will--there's a way!
As Peckish said, there really isn't much difference in the Brother 1500 and any other 9" machine. The Brother doesn't have a true needle up/needle down feature while some models of the Janome & Juki TL's do but not all so you have to know the difference in the model numbers but if you're using an old mechanical where you have to turn the flywheel to make a half stitch--you might not even care about that feature. Also, one of the Juki's has a built in thread cutter/snipper and I think one of the Janome's but again, some people don't want the thread snipped as they prefer to bury the tails and need them left a little longer.