I have read about some people who have upgraded to SSD in the hope of performance improvements, they didn't find much of one though. If you decide to go this route make sure you find a automotive HDD - most "IT grade" PC drives are not rated for the temperature variation and vibration levels in a car.
My view is that it is something to face into *if* you have a problem, as the preemptive work carries its own risks and given the number of 5F units on ebay I can't see it is a particularly high failure rate
