It was long overdue.
One thing you should know from the start - I can't abide anyone else working on my stuff. I will always try to do it myself. Working in car dealerships for over twenty years does that to you - you see a fair variation in workmanship. So the letter from Suzuki had been festering in my rucksack for six months but, then again, any corrosion present in my master cylinder could've been present for eight years now anyway (it is a K6).
Any signs? Sponginess?
Nothing. On original hoses, the lever still felt as good as ever. Fluid is changed regularly, or at least while I've owned it. It's not a solid lever, but the brakes are still adequate for hauling the old girl up - and light years ahead of my sixty year old Beesa:) What more could you ask for?