Their entrees are $9.75 and $9.25. The only non-alcoholic drinks they have are their Conga and bottled water. For 2017, I highly doubt the Conga would be included with a QS credit, so you're looking at $12.75 for your entrée and bottled water. QS credits are "worth" about $18, so even if they do let you use one, you're losing money.
Now in 2018 when alcoholic and specialty drinks are a part of the plan, it might be a better deal IF they participate.