Like you, I like
Katherine's closeness to the original spelling,
Aikaterine. I also like the fact that it's the most common spelling in the US (has been for awhile) so everyone knows how to spell it. That was an important consideration for me when I named my dd
Katherine (
Kate). Having said that, I think the spelling should complement the mn and the surname so I'd just wait to see how that works out. Keep an open mind. The combos you've picked out may change. Personally, I prefer
Katherine but in the mn spot, I strongly prefer
Catherine. For example,
Julia Catherine or
Laura Catherine just look right compared to
Julia Katherine or
Laura Katherine.