One other thing to consider is Russian's are basically a four-legged locust. They will strip a lush pen bare in no time.
Greeks are as hard on their environment, so if you keep them together and have any natural graze your Greek will be lucky to get 20% of it!

I've had Russians for 8 years and various Greek's for almost 30 and no tort is harder on their environment than Russians.

My lush outdoor Russian pens last 3-4 weeks max (early -mid June where I live). The Greek and Redfoot pens last well into late September.

Ernie