REI SteriPen Journey LCD

I tried out our new REI SteriPen Journey LCD today. We bought it a couple of weeks ago at the REI Flagship store in Seattle. It was just inside the door. The reason we bought it is that I need a quick, light, and simple water purification system for long trail runs. At $129 dollars, it was a little expensive but it has some great promised benefits.
First, it kills giardia and other pathogens using ultra-violet light. So there is no chemical taste whatsoever. It also isn't that heavy, it weight less than 1/2 a pound. I carry a bike bottle in my hand while I run. With the SteriPen, you pull it out of it's cover, press the button twice, stick it in the water and stir for 40 seconds to purify your water. Purify is the wrong word, disinfect is probably better. Once done, it displays two smiley faces. One for the battery and one for the process completing successfully.

So how did our REI Journey LCD work on it's first trail run? I used it twice in the first 7 miles to fill my bottle. It was great. Scoop up a bottle full of water, stick in the pen and then walk while it works. I'll need some sort of smarter carrying option while running than sticking it in my small backpack.
After I turned around, 7 miles from the trailhead I went to use the SteriPen Journey again. Push the button twice, stick it in the water....Double Unhappy Faces! I tried it a few more times on the run back. Luckily, it wasn't a hot day and I can run 7 miles without drinking, but I wasn't really happy about it. I ran 3 miles and tried again, no luck. I was tired of it, and ready to huck it.

After we got home, I pulled out the SteriPen Journey again and sure enough it seemed to work. Re-reading the manual, you have to dry it completely between uses. But the confusing thing is that the double unhappy faces means that the battery is worn out and the process failed because of that. The batteries are the originals, pretty darn new as far as I know. I'll chalk it up as user error this time, but want to test more to see if it is actually reliable.

So mixed reviews, I plan on giving it another test trip. I'll let you know if I get giardia or any other amoebic parasites from those original couple of bottles of water.
On my long long run this summer, I might just have to carry some backup Potable Aqua.

UPDATE 6/29/2008:
I did another run to see if it was just user-error with the Steri-Pen. Sure enough, an hour into the run I refilled the bottle and the dumb thing just wouldn't work. It would sometimes go for a second and then give me the single unhappy face. I gave it the mad face back.
Testing at home, it worked great. So what was different? After considering things, I tried shaking it a bunch before using it. Whammo, it didn't work. Running with it in my pack seems to make the Steri-Pen inoperable. Waiting 10 minutes or more seems to fix it. I don't have that kind of time on a run, so I will be returning it.
If you have a lightweight, quick solution for clean water on runs please let me know?