The mercurial and oft-controversial centre made a try-scoring debut for Championship leaders Bristol last week, having recently signed from Premiership Bath.
Henson, 33, will feature again when the promotion-chasing side arrive in South Yorkshire today.
Griffiths was, memorably, defence coach for Wales when Henson and company famously won the grand slam in 2005.
But he recalled: “I actually know Gav from further back than that as I gave him his debut for Swansea on the wing in 2000.
“I was there as head coach at the time and you knew he was talented. He used to just turn on halfway and drop a goal. And anyone who knows Swansea will know it’s a massive pitch there.
“Gav was just a different class. I was with him again with Wales for the grand slam in 2005 and that year, playing with the British Lions, too, was probably the pinnacle of his career.
“He’s stuttered at different times in his life and had lots of different chapters but I’ve always found him great to work with.
“I just hope he doesn’t have one of his good days on Saturday as Gav can still win a game from 60m out whether with a kick, a drop goal or a chip and chase.”
Griffiths added: “He’s a very skilful player. It won’t be easy for him dropping down to the Championship but I can see why Bristol have recruited him.
“He’s very versatile and can win a game from nothing. Gav’s a good signing for them and we can’t afford him too much time or space on the ball.”
Revived Doncaster are hunting a fourth successive win in all competitions after showing great spirit to prosper 30-13 on Sunday at Cornish Pirates with just 14 men. That is a second consecutive league victory after success over Yorkshire Carnegie ended a nine-game Championship losing run.
That has eased relegation fears but Griffiths said: “Anyone who has seen us would agree we’re now getting the results our performances deserved.
“We should have four more wins than we do but we haven’t and we have had to crack on.
“Hopefully, we can now build on these last two wins although we know Saturday will be one of the toughest games this season.
“I’m expecting a gutsy performance from us but we must be more clinical with our chances.
“We missed a few against Carnegie, Munster and again on Sunday there was some overlaps we blew. We can’t do that against Bristol.
“The biggest plus for me is the way the lads have not let things get them down.
“Obviously I was concerned but not suicidal despite others saying we were in a bad way.
“But the lads have shown spirit in bucketloads.”
Griffiths makes just two changes to the side that won in Cornwall last week. Leicester Tigers loanee Terrence Hepetema comes in for the suspended Bevon Armitage while Tom Davies returns at hooker for Richard List.