Don't compare them side by side as they are not the same!
I use both but on domestic my preference and in my opinion HWE is more suited to doing more different jobs and showing the customer the dirty water.
Dry fusion is excellent for commercial work although it does a very good job on domestics but is not as flexible.
Try doing stairs with a buffer!! I know they have a stair OP machine but it will only do the main of the stair not the edges or turns.
Dry Fusion can not do upholstery, there was a man in Stockport called Alan Wrigby who used to use the Activator to clean with and scrubbed it into the fabric but even he used to HWE the arms.
There is nothing wrong with either system but you may find that HWE has more options.
Shaun