Have you tried a SV650 yet, it’s considerably lighter than the ER6N, much cheaper
too as you can only get 2nd hand ones (assuming you’re after a naked one) and
it has a lower seat height.
The MT-03 is a hoot- I don’t think you’ll be disappointed if you go for it.
Watch for rear lock-ups changing down in the wet as you get used to the engine braking (there’s no slipper clutch like there is on the KTM duke).