Your best bet it to have it sprayed all white or all black in the short term and book it in with Jon and then just wait.
You'll only be disappointed all over if you go for a random with no experience. I've seen a number of frames done by other people that just look 'off' because of the lack of experience with the finer details. If someone doesn't know Kleins then they can miss the smallest thing which makes the biggest difference
Nice thing with Jon is he's a no bullshit fella with a cracking sense of humour who does things because he enjoys it and is passionate about it rather than seeing you as a pay-cheque. He spent time researching and talking to the ex-Klein painters to get things right and has set about sourcing parts and spares so that you only need to go to him. Think his long list is testament to his quality and sound approach.
I can't compare to Etoe as I neither know Martin or have seen his bikes in the flesh but you won't be disappointed with Jon.
I agree with pete_mcc, to match the colors should be do-able for others painters, but the details will make the difference i think. Debossed or decals, on the right place on the frame, how the colors fade into each other and so on, i think Jon and Martin did a lot of research to know how to paint them.
But i won't say someone else can't do the job, it depends a lot if he really likes to do it or that it is just another paintjob for him.....