Si,
Yes you are correct in saying that to apply to airlines (which I'm sure the majority of us want in time but good points made here about not being in tooooooo much of a rush to get there) you will need the IR.
However I know from close friends (ex-FI's) that, leaving aside the actual "target" if you like of 1000+ hrs for a moment, instructing is enjoyable, and importantly enables you to gain more confidence/general ability/airmanship etc (i.e. all good points)at a relatively early stage which will stand you in excellent stead for your flying later on.
When the time comes to tackle the IR, I would rather have 1000 hrs under my belt than not, when it comes to airline transition, again the same applies.
Plus if you do the IR with around 250 hours, currency could become expensive if a job does not materialise fairly quickly.
All in all, I really can't see too many downsides to instructing for a couple of years and it amazes me to think that for so many guys who are keen to attain a flying position, instructing is almost looked upon a bit negatively. Why ?? You surely cannot lose. Ok, maybe the pay isn't going to be wonderful (only for a while), but to let that be an excuse when people have got this far ?!?
Yes flying should be fun, interesting and if possible, varied. There are many years to come of trans-atlantic sectors, make the best of GA to your benefit while you can.
