well. Dot 5 fluid does not absorb the water like non silicon type does. so the water will be on a blob in your brakefluid, and that water goes to your calibers. that is one point. second is that there is not so much of higher boiling point, so you dont actually need silicon dot5 fluid, unless you really race hard. and it also cost more than dot 4.

silicone does damage your calibers faster, if you do not change fluid.

dot 4 fluid is good, when you change it at year interwalls. there will be little water on your fluid, but when you change it often, like once a year, it will be stay in good condition.

you basicly dont need special calibers, but you must know that you cant use dot 5 on all calibers because its silicone based. and when having ABS system on car, it can be costly, if some parts of ABS breaks.

and if you change your fluid to silicone one, you must make sure, there isnt any bit of old dot 4 fluid in. you must not mix them.