I have done a lot of 4-hands over the years (and those Dvoraks are HARD! - good for you!). I have found that most pieces divvy up the difficulty betweemn top and bottom quite well - I doin't see an obvious difference in difficulty. Perhaps this is because I see more "importance" to the bottom part, which to me provides most of the character of the piece, so doing the bottom part well can be difficult - the bottom person usually does the pedalling, and maintains the tempos - so there is extra responsibility there. I would also be surprised to see the "more technical" pianist be the top player - I would expect it to be the other way around. I personally prefer to play the bottom parts.
I'd love to know about good recordings too! The Slavonic Dances are such fun to play!!!