Our plumbers had never heard of it but I made them use it on Nick's recommendation to fix the shower trays and anywhere silicone would have been used.
So, our en-suite sink and cabinet were been bonded onto the tiles with Sikaflex. A few weeks later they had to be removed to get at the leak we had.
Two plumbers, a joiner, multitool, global fish knife and much swearing and it still wouldn't budge. Finally got it off and cracked the sink in the process (invisibly fixed by MagicMan).
Now they swear by it. - I've just used it to fit some 8mm U channel side on to the wall to take the son's shower screen and it's rock solid.