There’s no need to replace the whole device to meet ADA strobe compliance requirements if the strobe can be brought up to code. I believe that’s a purpose products like the http://www.cooperindustries.com/content/public/en/safety/notification/products/life_safety_notification/audible_visual_appliances/strobes/wheelock_series_rsspstrobeplates.html Wheelock RSSP are made for.
As for the replacing the actual strobe on the device, I’m not too sure on that. One one hand, as long as the strobe would be able to meet coverage requirements it would seem OK, but on the other hand, couldn’t it violate the UL certification of the alarm? Hopefully someone with more knowledge can weigh in.
(Also post # 1000 haha)