A friend told me that the one I have in my build is a single lane PSU, sooo the question is... any good PSU's that are twin lane that are around $100?
As far as power deliver there is little benefit between single rail vs dual rail. Dual rails sometimes run into issues if you try and draw to much power and each rail will have over-voltage protection on each rail that is going to be lower then the over voltage on a single rail. However that also means multiple rails are a bit safer. Now the chances of any decent modern power supply failing in a way that send to much voltage to a component and damages it is very small so....
In the end single or multiple makes no difference for the vast majority of people.
that's my build atm.