The owner of the kitchen I'm talking about has used Danish in the past and the stains round the sink area are absolutely horrible.
I'm gong to use one of the Osmo products (and likely the one they recommend for wooden worktops on account of it's additional water resistance properties).
The bottom line is no one has ever yet to my knowledge reported bad results for Osmo. The only downside appears to be the cost, whereas with all the other products the responses are mixed ie some good some bad. So there is a greater quality variation in all the choices except it seems for Osmo who do appear to be getting rave reviews.
I have used Osmo and Fiddes - I find Osmo slightly better. I doubt in many cases they have been used for long enough for long term assessments (much as I like them). How many problems with staining around the sink are caused by inadequate waterproofing of the grain in the cutouts? If the water soaks into the end grain under the finish it can't really be blamed on the finish.
I will also add that the Fiddes range also continually get good reviews (in my albeit anecdotal and not at all scientific poll). Not tried the Chestnut hard wax but I'm a big fan of their finishes and use 3 or 4 in turning so I rate the brand, just not heard much about this particular finish.
That would really be down to a case-by-case basis woodknox, some Danish oil products are usually significantly diluted already (75% or more white spirit is not uncommon on consumer-level versions) so any further dilution will just slow build unnecessarily.
If conditions are good there's nearly no benefit to diluting an oil or oily finish in the first place anyway, in warmer weather it's much better not to.