It seems (after some googling) that the Me 210 was horrible but the Me 410 was better. How much better is difficult to say.
The 210 had a rather short fuselage and the slats arrangement was not the best it seems. The 410 was changed in these respects.
See Joe Baughers presentation on
http://www.csd.uwo.ca/~pettypi/elevo...her/me210.html
Lars Sundin