Om 1 Vs Om 1 mk ii for macro photography

I am currently using the OMD EM1 MK iii for my macro photography and looking to upgrade to either the OM 1 or OM 1 mk ii. I was wondering if anyone has any experience with both bodies and if they though that the MK ii was a big enough improvement over the MK I to warrant an extra £400 (baised on used prices on mpb OM1 £849 and OM 1 mk ii £1,229 for both good condition)

I mostly want to upgrade for some better video capabilities (being able to shoot 4k 60 instead of having to resort to 1080p for slowing footage down). I do hear that the MKii buffer is slightly better which would be beneficial for focus bracketing big stacks consecutively which I do at the moment, but is that the only real advantage over the MK I for macro photography?