Hi Sam
Don't underestimate the low end of the 799. Although it's only 1100sqcm it easily covers the range of the i76.
Never used the 950, but i suspect it is a better version of the 790 (Moses version of i76).
The 899 is a bigger version of the 799 and has very similar ride characteristics. Just lower stall speed and lower max speed.
I only bring out the 899 for marginal conditions eg 10-15mph, otherwise i am on 799
This is 899
Yet to try the 999, but i am thinking it might be possible to go from 799 to 999 and skip 899