I love my Debit card. However, I also understand the desire to use a check for larger purchases.
When it comes to grocery stores, I rarely worry about check wielding people, since they typically use them so frequently, they write em out quickly. In fact, I'd say with all the processing when I use my debit card, writing a check could be quicker.
In the grocery store, the major hold ups are when someone argues with checker about a sale price, they start talking to the checker and they stop doing their job, or when the checker is just plain slow.
The only time I've ever argued with the checker is when they put in the wrong (more expensive) produce code for some tomatoes I bought, and refused to check through their produce codes to find the right tomatoes. I refused to buy them from them, because of their insolence.