You're a nice guy for wanting to save them some money, nothing wrong with that especially if it helps you gain more work in the long run. When I was doing some really soiled food joints I personally never gave my competition a second thought. My price was engineered for a certain profit and hassle factor and that was it. As long as you are making the profit you want and you can stomach the food joint carpet work the lowering shouldn't be a big deal.
Bought the only thing I can suggest is a pre-spray cocktail I eventually found that allowed me to clean the worst restaurant carpet imaginable with little or no agitation, Prozyme and Energy from CTI and then ProMax and Energy in the truck jug. May seem like a lot of $ in chemicals but not when you see how much time it saves in dissolving the load. Keep the heat at the jets screaming. I've been spoiled with a Savage propane heater and ran it really high 240ish on my restaurant carpets. I would be doing all my Chevy's carpet today if it wasn't late night work. Had it down like clockwork and left my 175 at home.