I have the Viking Mega Quilter - it's the very same machine as the Janome and the Pfaff Grand Quilter ... all 3 are made by Janome and they are identical as far as I know, except for their machine housing designs.
I've not had any problems with my Mega Quilter, took a little getting used to the hi speed & a mech. machine again - but it has been a real workhorse. I piece with mine as well. You do need to oil them quite often, depending on how much you quilt.
Ditto on using a NEW needle for every quilt. Always.
Quite a few quilters in my guild & retreats have these machines. I know a few who have the older Juki 98s too.
The Juki used to sell for less than the Janome-made ones (in 2007 when I bought mine) I don't know about current prices -