In my opinion, I have found that sometimes sales people will say anything to get you to buy 'their stuff' Guttermann is a great middle to top thread range in price and quality, I have used it for over 30 years of sewing and in all that time I have had no problems what so ever, I even use their 100% cotton quilting thread to hand quilt my bed quilts with, I have never needed to change to anything else. Just my opinion.
Gal