Considering I've liked all the episodes in which they have appeared...yeah, why not if there's a strong story to tell. The Crimson Horror was a bit Doctor/Clara lite and it was one of my favourite stories of Series 7.Love it. So if a spin off was that quality, bring it on.
I can see why Strax divides opinion, but said on here before, there was always a lot of humour with the Sontarans going right back to The Time Warrior, a favourite Pertwee story of mine. SM has just riffed on the original intent of the masterful Robert Holmes, I think.