The only drawback I see with the SteriPen would be the need for batteries and the lack of sediment filtration (not a big deal if you don’t mind drinking suspended particles). I currently use the SweetWater filter system. It’s bulky and it can be a pain to carry if pack space is limited. However, it works great and after 10 years it’s still going strong.
I have recently switched to a waist pack setup and now I’m thinking about going with this:
I relied on a Steripen Adventurer for 2 weeks in the Wind River Range last summer, 2 weeks in the Beartooths the summer prior, and in many trips to the Smokies with no issues at all.
I have used a Seychelle Water Filtration bottle for the last 4 years with no problems as of yet. It’s great while backpacking or while fly fishing on the river or creek, I just dip the bottle and fill up on the river, screw the cap back on, and it’s ready to start drinking, simple and easy to use.
Steripen works great! get the OPTI. I spent a week in the backcountry with 8 scouts and 3 adults using 2 steripens to meet our water needs (about 40L per day). Worked great and no one had any gastrointestinal issues during or after the trip. We were in the Chicago Basin near Durango, CO (home to a very large population of giardia-filled, mountain goats).
I purposely use a LED headlamp (Fenix Zebralight H30-Q5) that also used the CR123 batteries so I double dip in the back up battery stash.