Replacing Stair Treads

The old wood stairs in my brownstone are in solid shape but are made of carpet grade wood. Because I would like to have nice wood treads without carpet the contractor suggested refacing (?) the treads and risers with upgraded wood instead of replacing the risers and treads. I think it works like this

http://www.woodsthebest.com/Stairs/wood-stairs-treads.htm

Does anyone have experience with this and can you share the up and downsides of refacing instead of replacing? (pun intended)
Do the stairs squeak?
Is the height difference a problem?
What kind of wood did you use.
Thanks!

By hhitchc |