I think the question is also about the difference between buying from someone you know ( and you know how well, if he did, take care of his gear ) and buying it from a complete stranger.
So, if you know he took good care of it- it might be worth the cost difference- maybe.
The difference between 10,200 and 7,000 is moot- if it is not under warranty, then the shutter could go out in 3 clicks or 300,000 clicks. You never know.
EOS 5D III, EOS 7D,EOS Rebel T4i, Canon 70-200 f/2.8 IS II, Canon 24-105L, Canon 18-135 IS STM, 1.4x TC III, 2.0x TC III, Σ 50mm f/1.4, Σ 17-50 OS, Σ 70-200 OS, Σ 50-500 OS, Σ 1.4x TC, Σ 2.0x TC, 580EXII(3), Canon SX-40, Canon S100
Fond memories: Rebel T1i, Canon 18-55 IS, Canon 55-250 IS, 18-135 IS (Given to a good home)...