Maybe we could see a source that gives the 190D-9 or the 109G-10 a speed advantage over the XIV. I cant find one. Thats probably because the 109G-10 (440mph) and the 190D-9 (426mph) were not as fast.
That being said, published speeds are always under suspicion, I will say that the 109G-10 and the SpitXIV were probably very close (within 10mph) of each other at best alt.
As for the 109K-4, for what? it has the same specs as the G-10 for the most part? longing for a K-4, so you can go the same speed as a G-10 but say "hey, im in a K-4"?
I could see having a K if there was no G-10. The LW has all of their fastest WW2 rides, Me262, Arado, Ta152, 190D-9, 109G-10. There isnt anything left save the "secret weapons of the LW" like the Comet and maybe the Do 335 Arrow.
Give us the Stuka, thats what the LW needs.
Regards.