Questions about Samsung 860 Evo

I want to use the Samsung 860 EVO (500GB, mSATA) as accelerator cache for my DROBO 5D3 storage solution (gross capacity 5 x 4 TB = 20TB). This has an integrated accelerator bay with mSATA card holder and, as far as I know, can accept almost any mSATA cards apart from SandForce-based cards. Would you recommend the Samsung 860 EVO (500GB, mSATA) for this purpose? Or would anyone prefer the Samsung 850 EVO (500GB, mSATA)?

Samsung website says the warranty is 5 years. Here it says 3 years, is this right ? Even microspot.ch shows 5 years standard warranty.