AFAIK LW 4.17 & above will not upload to versions of LW older than LW 4.14, thus you are limiting options of the network. . LW Changelog
Personally I never liked LW 4.9 & thought LW 4.8 was better than all versions up until about 4.11 or was it 4.13.
LW 4.9 brought in the junk filter option which was experimental at the time & slowly improved in later versions. Though still needs training. There were also other changes in LW 4.9 I did not like how they worked, but that was me & IMHO on my setup & system.

I enjoyed LW 4.14 on my G4 (still using OSX 10.3 & 10.4). Now I use 4.16 and LW 5.x on different accounts on my intel macpro. With LW 4.16 I get the best of both worlds because I can both download & upload from versions older than 4.14, and I can upload & download with LW 5. I do not recommend LW 4.18. LW 4.16 version options we offer on the forum here: I use 4.16.6 however it does have some occasional annoying bugs that occur once every 2 to 4 months or so. LW 4.16.7 might be a safer option but up to you if you should decide to try LW 4.16. Older LW OSX versions; (Sorry misplaced my old LW 4.14 installer; sitting on one of my few hundreds of CD-RWs as an unlabelled LW version.)
(Due to the occasional 4.16.6 bug I mentioned, I now backup my library.dat file from the LW preferences folder fairly regularly or after any changes to shared files information. I occasionally backup the downloads.dat file from incomplete folder also.)

I am not sure how well LW 4.9 functions with the newer iTunes.

Sometimes LW downloads stop transferring to iTunes. What you need to do is (1) disable & re-enable transfers to iTunes within LW's preference settings. (2) disable & re-enable transfer & share on local network options in iTunes. (3) Restart both LW & iTunes, perhaps also reboot the computer.

Keep in mind LW stopping transferring files to iTunes can be an ongoing issue when LW becomes particularly busy or has been running for several days on end.