I still think that fixing the dropout is a better choice. Interesting that there are a number of suntour dropouts with failures in the same place. Maybe the welder could build fill in the triangular hole just a little to help that area out; seems like it's a weak point.

I really would hate to have a halfway decent bike with mis-matched dropouts. It would make wheel placement somewhat problematic and it will probably look funny and may actually be a little weak. I think I have some of those Suntour dropouts though.