I'm not sure, but i'll give you my opinion/guess.

1x coverage is older, and thus is much more widespread. If you live in an area which gets 'spotty' 3G coverage, switching the phone to 1x-only will probably save battery, cause then the phone no longer is searching for service half of the time.  However, i can see where this other site is getting this from. Did they explain why 1x could drain more battery? My guess is that because its an older technology, they don't invest in making its reception methods anymore, so it is possible that picking up 3G is more 'efficient', simply because newer antenna technologies/scanning methods could be improved over the older methods. But like i said before, this is purely speculation.

All i can say is, test it out! And let us know   Be sure to take a larger sample (like over a period of a month), to minimize/eliminate other factors that affect battery life.