Hey, Moose!
Some years ago I broke down and purchased a grinder. This came in very handy, since I grind chains for about 10 private customers. Some of these guys bring in 30 chains at a time. However, I find that I prefer filing my own chains, since it's very therapeutic, and helps give me a 10 minutes-to-the-hour break in the woods. Additionally, hand filing is a great skill to master, and keeps your chain sharp all day long. I touch up my chains a few times during the cutting day, but swap the chain if I damage it on a rock. Then I regrind it when I'm home again, and touch up the depth gauges.
So, it really depends. If you have 5 or 10 chains, and you file only for yourself, a file is more than adequate. If you need greater capacity and more speed, get a grinder. Otherwise I could not justify the cost of grinding vs. filing. There is a huge difference in price, and cutting with a hand-filed chain is just so rewarding!
My 2c.
Mike