Del Goatro is the best player on any surface and cannot be beaten by two prime Noserers at once(unless injured or tired of course).
The -er just makes it relative. Unless you think all the hard surfaces are the same speed?
Tho' arguably the difference is so negligible now that it matters not.
The difference are very negligible for sure, don't think we can even separate slow and fast HCs on the tour anymore, the differences are negligible at best.
Ironically, the tournament that most played like a fast hardcourt this year was Madrid, which was not even a HC event.