Which boat?

It depends where you sail, both boats are really popular, best looking at the nationals attendance figures for a rough guide and then going to your club to see what's sitting in the dinghy park. For instance at HSC, we have no 800s in the dinghy park just now but a good few 4000 but at other clubs the reverse is true. The 800 did take a massive chunk out of the 4000s market but you have to be aware of regional trends too. Up in Scotland, the MPS and 49er are really taking off just now and are showing a real growth in comparision to other classes but that will be different in other areas.

Having sailed both 49ers and 800's I,d say the only significant difference is the skill level required by the crew. On the 800 you can get away with a slightly less physical crew, who makes the odd mistake and you wont get punished too much. Weight wise the 800 is actually a better weight carrying boat than the 9er, contrary to popular belief. From a helms point of view the 800 is quirky and can be a arse in light winds whereas the 9er is a piece of cake until you reach 20kts. 9er can be difficult to launch and recover from narrow slipways and especially when you have an onshore breeze with a narrow slipway.
9ers are however cheap and there are a couple at Chew, Chris Gill, Ben McGrane etc. A good 2nd hand old boat £3000.
As for 800 a good 2nd hand boat £4500

Given your position If you have a guarenteed crew, get a L4000 or 49er if you havnt, get an RS600!

yeah if you need a crew....

also ben i have seen you have put up an add in the clubhouse saying you want to do sum crewing and at the mo, i am a crew/helm short

me sail a laser? ive never sailed a laser!

no sorry ben im not going to be there on saturday casue of a rugby match but might be down on the sunday