I have a 300 cx loader, I left mine out all winter last year and most of this winter, since I had my frame mounted plow attached.
The only issue you may have is if the loader settled in soft ground, it may be uneven or you may not be able to get under the masts. In which case you may have to jack it up a little, if you can't get close enough to hook up hyd lines. Mine shifted quite a bit last spring but I was just able to get under it.
If you have it on hard surface there should be no problems.
Well maybe I shouldn't say that, you may have trouble with hyd couplers not connecting due to built up pressure in lines. I have experienced that before.
There have been threads on that, and the best way to relieve the pressure. It can be troublesome if it's your first time.
The more I think about it there is a good chance you will have trouble with couplers, as it has happened to me 50% of the time I removed loader.
It's easy to relieve pressure on tractor side by moving the stick to all positions with engine off. For the lines on the loader you need to tap the ball at the end of the male connector, cover it with a rag and hold it good, because it will release a spray of oil. Only do that if you can not couple one of the lines.
edit: Beenthere beat me to the pressure build up part, since I am a slow typer I diddn't see his response
Good luck, JB.