On the Sennheiser Canada website only the HD 25-1 II is shown, I've emailed them to see if I can buy the other model here.
Sennheiser Canada can supply any of them without any problem - though they may have to get it in specially in their next shipment - it shouldn't be a problem.
But, if you want it and they refuse to get it, give me a shout and I'll sort something via the UK for you.
It's a drag that the second model has a shorter cable, I assume it's because these phones are geared towards the DJ market.
The HD 25 was never designed for DJs - it was originally designed for ENG (outside broadcast) use (HD 25-1) and studio use (HD 25-13). It was only later that DJs discovered it and now more are sold to DJs than broadcasters - but, in Europe, it's still the standard headphone for film and broadcast sound recordists.
The -1 version had a rt.angled cable so it would plug into Betacams without getting in the way - also, a rt.angled jack just twists when knocked and does not bend or damage the socket.
The -1 version is the most popular, especially with sound recordists.
teh 2m cable version was for DJs and for sound recordists who wanted to listen wjile the recorder was on the floor.
The -C version was for those (mainly DJs I think) who demanded a coiled cable.
The -13 (600Ω) version with a 3m cable was for studio use where a higher impedance does not load the circuit.
The -SP version was originally devised by Sennheiser UK for Concord. BA wanted headphones for concord, but didn't want to pay the price of the HD 25. Sennheiser UK realised that the split headband of teh HD 25 was expensive to make as opposed to the cheapo headband of the HD 414 - and - that the capsules of the HD 25 fitted the HD 414 headband. So a special version was made for Concord, using special 300Ω capsules, fitted to the cheap HD 414 headband.
Sennheiser in Germany then realised that this could make a cheaper HD 25 - hence the -SP version. BUT - you cannot have a cheaper headphone of the same quality as it would be commercial suicide - so the capsules of the -SP were downrated. Still excellent value, though.
I hope this helps explain things.
(Please note - I wrote this reply last night, but forgot to post it, I only posted it this morning when I woke up and realised I had not pressed "send")