if i am correct and i am sure that i am, there would be no difference between a 4+2 or a 4+1 setup since the first number (4) has to do with the VRMs for the cpu and the second (1 or 2) have to do with the RAM.
Dual Output PWM Controllers:
Many times we see a PWM Controller with two numbers instead of one, such as 6+1 or 4+2. So what does this mean? This means that the PWM can control two totally different VRMs! If a controller has the “+” then it has two separate but equal control loops. These PWMs are something recent and they became useful when specifications for processor power started asking for more than one input rail. The second rail is usually at a much lower current and different voltage than the main CPU power rail; however it can also provide power to another part of the CPU such as the memory controller (IMC)
i highly doubt there would be an armageddon using a 4+X board to overclock but you will most likely not get a very high and stable overclock. also consider not all VRMs are the same; there could be a board that has an 8+2 setup that is really a 4+2 and wont get as good of performance as another 4+2 board.
what where you looking at?