As far as I know Baachitraka the OM1 has a mechanically timed shutter, and the OM2n an electronic one...
OM1n is manual only, with the 2n having aperture priority, automatic or manual exposure
The 1 is manual flash, the 2 having TTL flash, in aperture priority, with T series flash guns
OM1n, no battery test function (Hey, who needs it? The batteries last years!) The OM2n has one (although I'm not sure if it has the dreaded battery drain problem)
OM1n Viewfinder displays only exposure info (under/over or correct)
OM2n Viewfinder displays selected shutter speed in aperture priority or exposure info in manual.
OM1n One mercury battery as standard (or one silver oxide with adaptor)
OM2n two SR44 batteries
Now, I'm not fully sure, but it seems like you can just use one of these batteries instead of the adaptor. I cant post links yet, but if you go to watch battery dot co dot uk and type in bp-px625 its the only page that comes up. I mention this because the voltage is 1.35 so should be fine...
Apart from that they are virtually identical, including the appearance. All the accessories are the same except the OM2n hot shoe will not fit an OM1n.
I myself have the same kit as you

And was in the exact situation as you too... not being able to decide between the two. As a personal decision, I have chosen that If I have some spare cash, I'll go for the OM1n. Simply because its a brickhouse, and there's no faffing about with the electronics. If the meter breaks down you can still use the whole camera with all shutter speeds and all (as far as I'm aware)
Like others say though, you cant go wrong with either mate. Whatever happens, enjoy it and have fun
