Which boat?

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!

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.

When we sailed the 5000, I loved her to bits. The major problem is they are really heavy boats, weighing in at wayfarer weight. The rig is pretty heavy too. You go for a swim and thats you basically messed up your race, well thats what we found. The heavy rig, combined with the sail area had us spending ages righting the boat using righting lines.  Another problem we had was that our club, at the time, was sending us round triangular courses. With the bags, you need to be in most cases sailing windward leeward courses to sail the boat to its maximum potential. With any wind, you need to be sailing straight downwind to be able to get the kite to sit at the windward side to drop the kite. I valued the crew I was sailing with because he could pull the kite round the front of the jib when we needed to and get the kite into the bag as quick as possible. From a crewing point of veiw, I reckon you need to be experienced to sail the 5000 effectively. Mind you the 5000 was bomb proof and we never had to replace anything through straight forward gear failures but we were always wishing she had a kite chute, well the crew was.

He actually sails an 800 and was in a lower weight range than us (slightly) and was saying we wouldn't be too competitive in all but really windy conditions. I think where he was coming from was we'd be the heavy guys in the 800 but about mid-range for the 49er. I think if you're about 130-140kg you'd be an okay weight for the 800, maybe even at the heavier end of the fleet which isn't too bad a thing because it means you should be able to control the boat better when its windier. We were also told that after sailing the 5000 competitively we might find the 800 easy, boat handling wise where as the 49er would be a step up and we'd enjoy her more.

I haven't actually sailed an 800 but we considered buying one when moving class from the 5000. We talked to our local RS dealer and they reccommended that for our weight (140-150kg) and coming from the 5000, we should only really be looking at the 49er or I14 to get the most out of our sailing. We've raced against 800 & they are much more comfortable sail in light winds because of their hull shape and not having such a big rig. There is a bit of a leap from the 800 to the 49er, considering the 49er carries much more sail and has more skiff-like hull. The 800 seems to be relatively forgiving compared to the 49er. The comparision that you read was probably the same one which I saw in "Dinghy" magazine, & seemed to hit the nail on the head between the differences in the boats.