First off to the OP 15 holes in 30″+ of ice with an ION is about right.
I have used the following drills in the past two weeks.
Ion
Strikemaster
Millwaukee / KDrill
These are my observations, so please don’t get any hurt feelings.
The ION cuts a bit slower than the StrikeMaster but the Strikemaster can’t open old holes very well. I know numerous people that have bent their augers trying to do so. StrikeMaster will fix them, I think it’s $75 to adjust the pitch.
Millwaukee / KDrill didn’t cut well at all IMO. Over the past week all I have seen is KDill users out drilling and they need to clear the ice chips 50 times per hole and they don’t get any where fast. When I was using one and watching others I think any other option would be better in 30+ inches of ice. (Love the KDrill on thinner ice)
There is a lot of energy wasted in clearing chips and resistance when drilling so much ice. There really isn’t an electric option out there that does well in 30″+ of ice.
IMO if you need to punch a bunch of holes use a gas auger. I love my electric for less than 2′ of ice and when drilling in the house. As for now I’m using the gas anytime I’m not drilling in a wheel house.