Hi Bill!
I am really happy with John Pearse... I am not going to switch brand for sure. What I do is to buy John Pearse 013-56 Jazz Rounds and then a lot of John Pearse extra 015 / 019 - usually 4 per set, the first two strings are the only ones that need replacement usually. The 13 and 17 that come in the package go as replacements for my 335 which uses the regular 013-56 gauge with La Bella Rounds. Even being different brands plain strings are usually similar.
Bill those Sadowsky are 15$... I find that a steal! I have the same feeling about Thomastik - they are good but too expensive... I play a lot of hours a day and my strings don't last much due to my sweating so I need the best price / quality ratio! John Pearse sets are 5.71$.. Thats one third of the price! And these are the best sounding strings I have ever tried... My luthier has done works on every guitar on earth and tried every strings that exist probably and loved this ones for jazz. But they do squeak... Lack of squeaking doesn't justify 3x times the price for me.
Oh and Sadowsky strings are made by La Bella - maybe you can find something on the La Bella catalog that does the same for a much cheaper price. I use La Bella Jazz Rounds on my 335 and love them - much smoother than DAs and they last longer also. They are a little more expensive but already come with an extra E and B - with the other extra E and B I take from John Pearse sets I am done
PS - They sell it at that price because they put the Bruno name there (only God knows how is name boosts sells on anything tone related but that's a whole other story). John Pearse Rounds are used by Peter Bernstein - they don't put it on the box and sell it at a ridiculous expensive price but that I call an endorsement. His tone is to die for... On his "Monk" CD you can really hear the sound of these 5$ strings.
PS 2 - I would like to try newtone but they are also expensive. I import John Pearse from the US but the thing is I order all my strings from juststrings.com so the shipping ends up being divided by all sets. Newtone would end uo being more expensive than John Pearse and I dont get theirs sets. I like 015 and 019 better than 014 and 018 and I find 058 a bit too much... So in the end I would have to change some of the strings and I dont think its worth it. Do you find the Sadowsky better than the Newtones? I assume you can buy the Newtones much cheaper in the UK...
John Pearse® Acoustic/Electric Six String Guitar Nickel Wound Jazz, .013 - .056, 2900