imac 2015 i7 vs Macpro 2013


by looking at the benchmark results seeing the maxed out imac 27 inch 2015 with i7 4.0ghz looks very good at the single core performance and quite ok at the multicore performance. i now have a macpro 6.1 6core . so according to the benchmark test the imac would be much faster in single core action, which is needed quite often i suppose.
Did anyone make the change between those 2 systems?
The reason is that the imac is pretty cheap to get nowadays and im afraid the price of the mac pro will sink very much once the new mac pro is announced.