I think if it is not a financial burden, then it is worth the extra 4k to hit the 3ct mark, if not for visual/"objective" reasons, then certainly for psychological ones!
And BTW, K is a lovely color and still faces very white in most circumstances. Only a very educated diamond enthusiast would be able to detect the tint (based on my experience with me own K/L colored diamonds). I don't think the tint is a bad thing anyway, but there is a marketing "stigma" that some need to overcome.
Off-topic for a sec here but I just have to say personally, I kinda hate the whole "surprise" tradition when it comes to wedding sets. Or other expensive jewelry. I would hate to wear something every day that was really nice and really expensive but not what I really wanted. JMHO, of course. I know other women do like a surprise.