I see what you mean.What I'm trying to highlight is that Zangoose can work above average without the use of Toxic and Poison Rampage. The fact that getting poisoned would be beneficial to Zangoose is the most attractive niche.
That set works well with and without being Poisoned, taking full advantage of Zangoose's Power while keeping it in tip top condition, for a while.
I myself will play around with the SD set because it reminds me of Ursa, but I'm hoping it doesn't leave like Ursa :'(
It's like "well, here's a CB/CS set. It works pretty well in my op- oh i just got poisoned. RAGE!!!"
It's a good way of using Zangoose IMO; maybe the best way (especially the Scarf one. Zangoose is a nice revenge killer).