You may indeed be aware of lots of faulty ones that go up in smoke, but I bet you have never seen a good one go up in flames.
Its a £50 easy fix, and could be considered as part of the maintenance required in keeping one of those cars alive and in tip top condition.
If you are not performing such an easy fix as this, then what else are you avoiding?
Fix it and move on . . . . Its not that difficult

Ah but I have, replacement batteries have leaked on number of examples, and boom!
No, I`m not talking about ones that have been inadequatley repaired with traces of corrosion still on the circuit board and non approved batteried being fitted, I`m talking about GOOD and GENUINE NEW items - I have never heard of one of these failing within a five year period, and neither have Sigma.
And before people ask, no, thats not any form of life expectancy, its a figure that was merely used as an indication.
And also, I have no personal problem with those that want to replace their own batteries, its a good cost saving exercise, just make sure it is done properly, and that ALL of that corrosion is dealt with and chemically neutralised, and that you do not simply solder in a new set of batteries - because if you do , you will be asking for trouble.