You should have no problems with your Slingbox 350 in conjunction with the Roku or the iPad Mini 2. These are all fully compatible; for reference, I'll link the Compatibility article below, just in case:
I hope this helps!
Sling Media Technical Support
I decided to buy a mini Android tablet. It is an RCA 7 Voyager II running Android
5.0 Lollipop. I was not able to install the free version of Sling Player.
It says it is not compatible with the device. I had to purchase the Sling
Player for Tablet. I kind of feel ripped off.
On Tue, Dec 8, 2015 at 9:08 AM, Samantha.Sling <firstname.lastname@example.org>