I have played with and against many different 3.5 guys in 7.0 mixed. I have never seen one who could S&V effectively, and most won't even try.
I think the problem is that some 3.5 guys have nice hard serves. Their serve elicits weak replies. Rather than come in, they just hit the next ball as a groundstroke (preferably FH) and win the point that way.
The other issue is that some 3.5 guys are horrid volleyers. Just horrid. They aren't coming in because approach volleys are too difficult.
There are a lot of 3.5 women who make a living coming to net. I think the reason is that the returner isn't likely to smoke the return so hard the server cannot reach it. Also, a lot of 3.5 women take instruction and have better hands for that first volley.
-- Random Error Generator, Version 4.0
-- Master Moonballer