Tested second time with the same setup:
16:08:00 10.100.4.47:2457 Requested GET /NewFolder/
16:08:00 10.100.4.47:2457 Sent 1201 bytes
16:08:00 10.100.4.47:2457 Served 1,03 KB
16:08:00 10.100.4.47:2457 Got 363 bytes
16:08:01 10.100.4.47:2457 Requested GET /NewFolder/~upload
16:08:01 10.100.4.47:2457 Sent 2331 bytes
16:08:01 10.100.4.47:2457 Got 370 bytes
16:08:01 10.100.4.47:2457 Served 1,30 KB
16:08:01 10.100.4.47:2473 Connected
16:08:01 10.100.4.47:2473 Got 370 bytes
16:08:01 10.100.4.47:2474 Connected
16:08:01 10.100.4.47:2474 Got 370 bytes
16:08:07 10.100.4.47:2457 Uploading small_test_file_1.txt
16:08:07 10.100.4.47:2457 Got 7430 bytes
16:08:07 10.100.4.47:2457 Fully uploaded - 2,14 KB @ 43 KB/s
16:08:07 10.100.4.47:2457 Uploading small_test_file_3.txt
16:09:02 10.100.4.47:2473 Disconnected by server: inactivity - 623 bytes sent
16:09:02 10.100.4.47:2474 Disconnected by server: inactivity - 111 bytes sent
16:09:08 10.100.4.47:2457 Disconnected by server: inactivity - 5448 bytes sent
16:09:08 10.100.4.47:2491 Connected
16:09:08 10.100.4.47:2491 Got 453 bytes
16:09:08 10.100.4.47:2491 Uploading small_test_file_1.txt
16:09:08 10.100.4.47:2491 Fully uploaded - 428 B @ 20 KB/s
16:09:08 10.100.4.47:2491 Uploading small_test_file_2.txt
16:09:08 10.100.4.47:2491 Fully uploaded - 1,72 KB @ 88 KB/s
16:09:08 10.100.4.47:2491 Uploading small_test_file_3.txt
16:10:08 10.100.4.47:2491 Disconnected by server: inactivity
HFS received the first one and got stuck on the third (skipped second) file. Then after a minute it uploaded all three again successfully...but this time no OK notifications..only white screen in Firefox.
Edit: Out of curiosity, I also tested with small (>1kB) binary files and got about the same results as so far with text files.
Edit2: Same thing with a bit bigger (~10kB) files...
Edit3: Big (~1MB) files still upload is a split second without any problems:
16:25:53 10.100.4.47:2804 Connected
16:25:53 10.100.4.47:2804 Got 407 bytes
16:25:53 10.100.4.47:2804 Requested GET /NewFolder/
16:25:53 10.100.4.47:2804 Sent 1051 bytes
16:25:53 10.100.4.47:2804 Served 1,03 KB
16:25:54 10.100.4.47:2804 Requested GET /NewFolder/~upload
16:25:54 10.100.4.47:2804 Sent 1279 bytes
16:25:54 10.100.4.47:2804 Served 1,30 KB
16:25:54 10.100.4.47:2804 Got 733 bytes
16:26:04 10.100.4.47:2804 Uploading big_binary_file_1.pdf
16:26:04 10.100.4.47:2804 Got 8236 bytes
16:26:04 10.100.4.47:2804 Fully uploaded - 1,33 MB @ 11642 KB/s
16:26:04 10.100.4.47:2804 Uploading big_binary_file_2.pdf
16:26:04 10.100.4.47:2804 Fully uploaded - 1,81 MB @ 10566 KB/s
16:26:04 10.100.4.47:2804 Uploading big_binary_file_3.pdf
16:26:04 10.100.4.47:2804 Fully uploaded - 1,98 MB @ 9397 KB/s
16:26:04 10.100.4.47:2804 Requested POST /NewFolder/
16:26:04 10.100.4.47:2804 Sent 2650 bytes
16:26:04 10.100.4.47:2804 Served 1,00 KB
16:26:05 10.100.4.47:2804 Disconnected by server - 7396 bytes sent
16:26:05 10.100.4.47:2809 Connected
16:26:05 10.100.4.47:2809 Got 407 bytes
16:26:05 10.100.4.47:2809 Sent 809 bytes
16:26:05 10.100.4.47:2809 Disconnected by server - 809 bytes sent
16:26:05 10.100.4.47:2810 Connected
16:26:05 10.100.4.47:2810 Got 407 bytes
16:26:05 10.100.4.47:2810 Sent 809 bytes
16:26:05 10.100.4.47:2810 Disconnected by server - 809 bytes sent
So this obviously seems to be a size related issue...