Question:
Does anyone have experience with the portable water purification systems for backpacking or camping as an alternative to the tables? If so what brand do you recommend?

Answer: It makes all the difference where you're hiking. I use a Pur filter, which removes everything except viruses. It's been fine here in Pennsylvania. No member of my party has gotten sick.

If you are a truly hard-core hiker, check some of the para-military catalogs for a purification straw. It'll do about 4 quarts before becoming unsafe. Purification is a must, especially if you are in the Pac-NW. The St. Helens eruption did a number on the glacial supply. Members of my party have become sick from glacial runoff since the eruption