The new Infinity Ultra has a different design than the old one. It has a spring but I don't think the spring helps reliability. CPF'ers generally prefer the old design.
Peak LED Solutions (
www.peakledsolutions.com ) makes some nicer 1AA lights that cost a lot more. Supposedly the Arc AA will be re-introduced before the end of this year, but I wouldn't hold my breath.
For 1AAA lights, either the Arc AAA (now available again,
www.arcflashlight.com ) or Peak Matterhorn are far better than the Mag Solitaire.
For a less expensive, extremely waterproof 2AAA light (about the size of a 1AA light), try the UK 2AAA eLED, about $12 from
www.brightguy.com .