The medical grade of silicone that bobby uses will outlast us all. He only uses the best and most expensive quality products available. You cant say the same for the big companies. Bobby is a guy who stands behind his work and products.
Any serious collector would know not to have their peices in direct sunlight, weather it be resin, polystone or silicone. As far as accrylic cases are concerned, theres nothing wrong with using them to keep out dust, but when dealing with a silicone peice, you want to be able to look at it up close with out the case impeding your view. I have accrylic cases for alot of my resin peices, but wont be having any made for my future silicone peices. Simply dusting them regularly with a air can and light duster is fine. On top of that, I think bobby would tell you if you REALLY needed a case for silicone seeing as he has his own private collection of silicone peices displayed out in the open with out cases, some peices going back 7 to 8 years.