these two aren't two totally different quads like some seem to think. as for the mechanical differences, they are built on the same chassis and have the same motor. mechanically, i believe they are identical minus the exhaust and clutching. the difference in weight that you are seeing is due to the body and the fact that the sportsman 1000 comes standard with a 2500Lb. winch. you mentioned mud/water and trails which tells me you'll be much better off with the sportsman as it offers much better mud protection than the scrambler does. if you're doing mud/water you'll definitely need a winch as well which is standard on the sportsman whereas you'll end up spending even more money to add one if you were to buy the scrambler. the scrambler also offers very little in storage/rack space compared to the sportsman.most trail/mud riders are always packing extra stuff which will be an issue if you were to go with the scrambler.
if you do any night riding, also take note that the sportsman has the third headlight while the scrambler does not. another thing to consider is that the scrambler comes with the most terrible tire to ever come on an atv. lol! the carlisle 489 IIs that come on the scrambler are only 4 ply and very prone to flats. they also don't seem to wear too good. the carlisle PXTs that come on the sportsman have a 6 ply rating and seem to last longer over the 489 IIs. i will say that the scrambler does come with led lightning but at the price of led light bars these days, you can easily pick one up off amazon or ebay for roughly $70 and it will offer a hell of a lot more light than the stock scrambler. the biggest edge the scrambler DOES have is the Fox shocks but polaris does offer them as an upgrade and they can be found below the retail price for just under $1000. it also doesn't have engine braking which some love and others do not. i personally prefer the engine braking of the sportsman.
when thinking about it, you could buy the sportsman, add a clutch kit and the fox shocks and you'll have a much better machine for the same amount of money than if you were to buy the scrambler. ;-)
Well yeah, I see what you're saying. I really don't need the rack space though, I could just carry a backpack. I love the looks of the sportsman but it weighs more though it has a winch, etc so I'm not sure. I'm going to be doing some hardcore mudding, can the sportsman take it?