They're fine if you screw them all the way down and just never try to use the tremolo function*. A true hard tail is better for overall pick attack/initial sustain, and won't suffer from tuning stability issues if you don't have either a block or strong enough springs holding the 6-point trem down inside the body cavity, but the 6-point vintage trems are OK in that configuration. If nothing else, it's a lot less work to set up than a Floyd Rose, but god damn, a Floyd that is properly set up and intonated can stay in tune for weeks at a time. That initial setup on a Floyd -- especially if you change string gauges -- is absolute hell, though.
Tuning stability problems with Fender-style bridges are often a problem with strings binding in the nut slots, especially on the MiM and Squier models. A little bit of graphite lubricant in the slots can alleviate this, unless the slots are too deep or too narrow, in which case, someone (preferably a qualified tech with the right set of gauged files) will need to do some cutting and/or shaping.
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*If your saddle height adjustment screws are long enough that you can lift the saddles up to compensate for the bridge plate being lower. Otherwise, you're getting into weird bridge plate shim territory.