If a racer like Gui said that it must be true. I specially liked the bla bla part of explanation. Realy good !
in theory there is a small difference. Look at the polar charts for my boat (Beneteau Oceanis 423):
You can see that the best VMG is achieced on different angles for different amounts of wind. But a difference is so small that probably Gui's advice was the best possible.
Here is relevant data for my particular boat:
wind in knots 4 6 8 10 12 14 16 20 25 30 35
So: One should tack differently in stronger wind - but in real life - look at the tell tales (or how are they called in English) and the sails.
If I singlehand I just hit the tack button on my autopilot (set to 90deg.), then I adjust the sails for beat, then I fine tune the course. If I am in the mood I trimm the sails a bit and of course handsteer to follow the slight wind shifts.