[bbartlog]

It would be possible to obtain a general answer to your question if you had access to all of the SNG stats from startracker or sharkscope. You could look at the distribution of ROI for both O8 and HE SNGs and see where the distribution was wider. If one type of SNG allows a winning player at the 99th %ile of ability to maintain 24% ROI over thousands of games while the 99th % player for the other only achieves a 19% ROI, then you could say fairly definitively that the former game allows for a greater edge.
But you would need a subscription and a lot of patience to mine the data, unless you could prevail on them to let you run raw queries against their database.