First Sikaflex is a brand name. You have to define which product as they have a variety.
Second, if they could really get 15yrs reliably without any attention, manufacturers would have switched over long ago. As much as people like to go on about planned failures, they would jump on a cheap fix that was drastically better.
Assuming it is chemically compatible with your roof material (they aren't all the same), it may work OK but I wouldn't risk not keeping up on the maintenance as it could be a very expensive experiment.
Also, are you creating a problem for the next guy. Is the dicor compatible if the next owner puts that over the top.