I bought my Strat used, It didn't have one. I bought one, My shirt buttons were getting snagged on the springs

I hate the look of a Strat with no back plate so you can count me out. As far as changing strings just push down on the trem a bit and out they come.

This is a good question. I've heard lots of things over the last 35 years, from easier access when changing strings or a broken string to slightly better sound, or just being lost in the touring shuffle. My cover is not on, but I would have to have dog ears to tell the difference in sound, I just find it easier to adjust things when needed.

Most people take them off for better access to the strings and springs.Jimi Hendrix used to get some of his strange effects by flicking and yanking the springs.

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'65 Strat,65 Mustang,65 Jaguar,4 more Strats,3 vintage Vox guitars,5 Vox amps,'69 Bassman with a '68 2-15 Bassman cab,36 guitars total-15asst'd amps total,2 vintage '60s Hammond organs & a myriad of effects-with a few rare vintage ones.

I use a pair of needle nose pliers to get the string balls out if they do not readily fallout when pushed. I haven't found a need to remove the cover or change the holes.

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You're only as strong as
the drinks you pour,
the tables you dance on,
and the friends you roll with.

I think that it's personal preference for sure. Mine is on, my neighbor has a red Eric Johnson signature Strat and he doesn't have one on, not sure if it came with one or not. To me it looks good on or off. Since mine came with it on I just keep it there. If I need to remove it for set up or string changes six screws are not a big deal. Good question though.