The Clam drill adapter is an excellent option, very light and compact. I would have gone that route if they would have come out with them before I bought my Rapala gas auger years back. I have a clam mounting kit on the front of my ATV for my gas auger so weight and size is not an issue.
Both are great ice fishing tools to get to the fish and as far as the purchase cost they would be close but operation and maintenance cost will be a lot less with the battery drills
Good luck and keep us posted