I had my babylock espire(Predecessor to the symphony) for 2.5 years before upgrading. It was not picky about threads. I used any and all threads in it. It handled quilt seams well but I didn't try denim or anything like that on it so can't comment on how thick of seams but definitely better than my low end mechanical brother for sure. I didn't have any problems with it in the time I owned it just upgraded to a machine with more features. as for time sewing on it it depends because I tend to sew in spurt where I sew everyday for a while and might not touch my machine for a few months or weeks depending on time and projects. It was a very solid machine and I was happy with it for the time I owned it. I love my vseries way more though IMHO its better built