Deffo, just stick with just the Xenons / headlamp washers at a £5 a month. That's a bargain for £700+ of options.
Like you, I'm still keen to stick with swapping to another 330d M Sport (my last car was also a pre-LCI 330d M Sport LOL).
I could tell quite a difference in ride quality moving from pre-LCI to LCI E90. I was very impressed with the LCI and glad I swapped from the bloody awful crashy pre-LCI M Sport suspension.
Not sure if you have a pre-LCI? If so, then I'd say you'll be able to tell a
massive difference from the pre-LCI E90 to F30 M Sport at least in terms of ride quality.