The blade runner sure seems like a great idea! I didn't think about the final drives being an issue. I guess it really depends on what you end up doing with the thing. I was hoping to here from someone who has one, and what they use it for, specifically.
Well I don't know if the drives are an issue, however they are hydraulically driven and would have relief valves, unlike a proper bull dozer.
However the blade is not as big as a comparable sized dozer and you can loosen the material to be pushed up with the bucket, sort of like rippers on a dozer.
The beauty I can see of the concept is that the BR can be used as a part time dozer, grader and excavator. None of which it would do as well as a dedicated machine but then you have to figure out the cost of buying, maintaining and staffing a dozer, excavator and grader. Obviously on a big job you would want lots of machines to do the various jobs all at once but on small to medium sized jobs a BR might be the way to go, particularly looking at transport and running costs.
I really think it is a niche market machine but there are a few used ones on the market, this doesn't look too bad
http://www.machinerytrader.com/list...u=KOBELCO&Mdltxt=ED190+BLADERUNNER&mdlx=exact bit rough but has lowish hours.
Another thing to look at is to rent one for a job and see how it goes.
If you are serious about a BR I would try and find some operators in your area who use them and ask them about it.