Is the strength of the coffee weaker as I increase the cup size or is it the same? Would I have to use 3 K-cups (small size) to have the same strength of a large mug-full? I do not want to waster k-cups in experimenting..
It's definitely weaker. I find that it's very difficult for me to enjoy a k cup coffee brewed with more than 8 oz (some demand no more than 6 oz.). Any more than that, and there's not a strong enough coffee flavor. Green Mountain does make some "travel mug" k cups, so those let you do a little more larger drop. Even with these though, I still don't like to go over 10 oz.
Some people love the K-cups, and some people just can't get their coffee to come out right. It's difficult to manipulate your coffee results with a K-cup. With a drip coffee maker, you can adjust the amount of water and coffee to get it where you want it. I guess that's why I was never tempted to get a Keurig machine.