I've got an 04 Five, and have had the following forks on it.

90-130 Talas
110-140 Pikes
150 Revs

All of those exceed the stated maximum of 125mm, despite the fact that the Talas came with the bike! I will say it's a bit more wandery on the climbs with Revs on. 140 is not a problem IMO, should be better than 100 🙂

Flat front to the swingarm = 04, curved edges = 05.

/geek

Actually, I think I could be wrong about the flat front, the 05 might just have a slightly different down tube. Google Orange bikes 2004 and 2005 and all the data is still up there. Mine has 5.1" travel, the 05 has 5.5" and is rated for up to 150mm forks according to the marketing guff.

Anyway, I don't believe that changing spacers would help much, since with a longer fork you'd be changing the head angle however many spacers you have. It's not awful at climbing by any means, and you do adjust by shifting your weight slightly further forward on steeper climbs. If it worries you, you could always get a u-turn rev and wind them down for the climbs. It will be worth it for the downs, I assure you 🙂

FWIW – I've been using 130mm forks on my (ancient) Sub5 (which I think came with an 80mm fork?). Yes the steering is a bit wandery, and yes you need to shift the weight forward on the ups. This is well beyond the bike's intended geom' – but it is definately better fun going down. So, in short – with the Sub 5 you can definately 'get away with' longer forks than the bike was designed for.