Hmmm, some good thoughts, figured it would be a stretch to go above a 32. There isn't much I encounter that I can't go up in 39/28, so 38/32 should be more than enough.
Currently wanting to stick with 1x as I'm using a MTB srm for the bike with 120 and 80 bcd, so double rings are a bit unnecessary.
If you are running a SR with a 32 (and you might get away with it 1x on along hanger) you are outside the design spec for largest rear sprocket but then by running 1 x on a 38 in some ways you are a bit off-reservation anyway!
You may lose a bit of accuracy in the middle of the cassette. If it's 2015+ rather than pre 2015, the accuracy loss will be much less as the Embrace system will bring to top jockey up and forward a bit as you shift towards the middle and smaller sprockets & you have more freedom to play with chain length to optimise that, too, in a 1 x system. 2015+ RDs also give you more options & range as far as B-Screw / H-Screw adjsutments are concerned, to optimise top jockey vs cassette position.
J-Tek x Shimano / 10s - it's an option but depends what is meant by "shifts perfectly" - I'd say "shifts acceptably". All the J-Tek devices to is apply a linear modification to cable recovery vs mech movement. The problem is that Shimano cassettes and Campagnolo cassettes have two different approaches to sprocket spacing and that messes with really accurate shifting when RD & lever are intermixed. Some users notice, some don't.