I'd never used one on my Janome, but when I got my Pfaff QE4 I noticed a huge difference! Fabric would invariably disappear down the hole and I'd end up unpicking knots and have frayed corners.
Apparently it's a problem recognised by Pfaff and I got a free straight stitch plate with the 'Quilters Bonus Pack' or some such.
Luckily I can set the machine to remind me when the plate is on so I don't break needles by trying to zig-zag with it on, lol. I've never encountered a problem with FMQ with the ordinary plate.