Mounting expensive foil caps in (comparatively cheap) speakers
like these feels to me like polishing the inside of the cabinets
or fitting 200$/meter cables and gold plated terminals.
It may feel good and if you have the right instruments for measuring, maybe you can
actually measure something but it is really overkill and not worth the cost.
But that's just the opinion of grumpy old me.
I have mounted very expensive caps in even smaller speakers at owners orders
but if they ever felt any difference, I didn't hear about it.
In larger (and better quality speakers), there is a little
performance bettering to achieve. One you can actually hear, the Pentas
being a good example. Intertechnik caps is also what I normally use.
I must admit to prefer blowing a resistor rather than a
driver in case of overload or amplifier failure.
It won't change a thing soundwise to "upgrade" the resistors.
Martin