I had credit card offers for Office Depot that I used to average about 8% back from Office Depot. I tried to but unfortunately could not use those to then buy VV from Giftcards.com to stack, I am hoping I will be able to use them and stack at Kroger. So yes, the real benefit comes from combining and stacking as many offers as possible. Just buying from a place like OD with only the in store offer only comes out to a few dollars, generally not worth the gas of going out of your way. Combining with credit card offers, then online offers = gold.
Edit: You could wait and see if Dosh puts out an Office Depot offer, etc. Dosh has a good record of paying out even with GC purchases at places like Office Depot, and if your card is linked and they have a CB offer that would add an additional few percent. It really all depends on the offers, what sites are linked, etc. With Giftcards.com the 5% back with 6% from Capital One Shopping was a real good offer (this was not the Captial One Credit Card Portal but their Shopping App).