I used the Sawyer picardin repellent on a backpacking trip this past weekend, and it worked well.  I still used Ultrathon (with det) on my Quetico trip in July, in addition to permethrin on clothing.  I think that the key is permethrin.  It works very well, and if you don't leave too much skin exposed, then either deet or picardin will work, but picardin does seem less harsh and didn't affect my gear.