[villagetinker]

I did the entire house, tiled area about 1800 square feet with a product from Grout Shield, it is very similar to the Mapie product at Lowes and color matched the original grout. Took 2 weeks about 3 to 3 sometimes 4 hours at a time to move furniture, clean floor, and apply colored grout sealer, then replace furniture. I used a wheeled stool (like used in automotive work) to save my knees. This has held up very well for several years, and the cost was $60, and I still have product for touch ups if necessary.
I used the Mapie product with I tiled the lanai, for some reason the grey grout dried in slightly different shades for grey, the colored sealer fixed this problem.

So back to your question, I would definitely have the grout cleaned and color sealed, and make sure that whoever does the work leaves you with some extra sealant. In my case the color match was so good that I actually missed a couple of areas which showed up immediately when the floor was mopped.