Sadly, I never managed to go passed the "my editor cannot show syntax highlighting for a mix of languages." :/
As for 'out of order programming', I think that TANGLE-style reordering is a lot less important with modern programming languages: they don't do one-pass compilation and so can deal with forward references. Note that most of the cross-references in Knuth's program could be replaced with function calls or constant names, rather than the semiautomatic inlining that WEB performs.
I've had some success in writing literate programs in a Markdown file, with a small script to extract the code blocks into a file for execution. This seems to work fine, at least on a small scale, and is very easy to implement and then extend if needed.
Edit: and by “small script” I mean:
import sys
code = False
for line in sys.stdin.read().splitlines():
if line == '```': code = False # End block
if code: print(line) # Only output block contents
if line == '```md': code = True # Start block
However, as soon as I start using noweb syntax for "out of order" programming, I stumble into long standing bugs (references are not always found, links in the tangled code are broken, detangling does not work, etc...)