although it's damn hard to find a copy, especially when EBGames has relegated PC games to one standalone rack at the back of the store (the console 'virus' sickens me

). I think the Gold Edition is more prevalent as opposed to a 'standalone' 1.5 Add-on. I just bought the Gold Edition for $30CAD and it automatically upgraded my 1.4 to 1.5 I then added TMO for 1.5 and RSRD for 1.5 so I'm back to the mod situation I had with 1.4
I use SH4 Speech as well so the immersion factor is that much better IMHO.
I'm still not sure that there's a HUGE difference between 1.4 and 1.5 (I don't play the U-boat side so may be missing something). The graphics are better, the loadtimes are faster and the GUI has been tweaked. I'm only a couple of missions into a campaign so perhaps haven't been exposed to all 1.5 has to offer (i.e. special abilities etc).