You may have to be patient in waiting for a response. Modern brand implements are carried by my New Holland dealer, but I don't know anyone who owns them. They seem to be well made and spec'd properly. I do wish they published the total weight of their boxblades like they do their rotary cutters.
As an aside, I noticed the online add for boxblades specified a tractor horsepower up to 50 drawbar horsepower, but when I looked at their online manual, it said 40 hp. Considering that, I think I'd want to get something in writing on my sales contract that specified the size of tractor the blade was being purchased for. The online numbers could change and then you'd be left with only what the Operator's Manual says as a reference for warranty work.
If you are close to the the Beaumont, TX location of Modern implements, that would seem to be a plus for getting repairs or parts as needed. They certainly don't seem to be a fly-by-night outfit. The galvanized coatings seem to be a good idea, but you have to consider if you ever do any welding on the implement, being galvanized may not be the best.