The x2 is in a league of its own. It rides like nothing else. It carves in a very unique waynand wants to be laid completely sideways sometimes to make a corner. They can be purchased inexpensively and you will be part of a large tuning family. It is a part of history and anytime i have mine, people will want to just talk to me about it.
The limitations are many. The biggest limitation is water ingestion, as the hood is a very bad design (some modifications help). The seat just pops off at times or the latch breaks all together (i am using a gp1200 latch). Age is also a huge factor, as many are old and have corrosion, rusted be plates, bad electrical components, etc.
The came with a 650 motor and the earlier motors had a small 28mm carb which sucked. Any model with less than a 38mm carb will need an upgrade (my 650sx had a 44mm sbn tuned by team scream and it worked real good). They can be plenty of fun to ride all stock and i wouod encourage you to keep it stock or stick with a modified 650 (pipe, milled head, prop, etc). They are difficult to work on as the motor sits under the steering and prevents access to anything behind the motor.
There are of course a wide range of upgrades, but the engine compartment is very limiting. 750 and 800 motors bolts riht in, but the rest of the componets are issues. Only the 650 pipes bolt in without modifications, and any oof the bigger parts require a hodge podge of nonsense (i have a westcoast 650 manifold, 750 head pipe, superject chamber, smashed in gas tank, modified waterbox, larger outlet). Dual carbs fit, but many air filters hit the hull on the rear carb, and stock airboxes dont fit without modification (remember water ingestion an terrable hull design is an issue. I am using a modified xl 760 airbox). Bigger motors come with bigger props, and none of the new 750 props bolt in as the pump is different, so you need a modified prop or a pump swap. Electronics are usually just strapped to the gas tank. Some people even put 1100 triples in them.
All in all, most of the headaches are voluntary. A stock or lightly modified clean 650 works well and is fun to ride. You dont have to go on the quest for more power.
The deal you are looking at looks nice, but is a little hih for my liking. It would make a great set as you could ride the b2 if you ever have issues with the x2. The green b2 is also the model that comes with trim, which is nice.
The decision is yours. I personally have a x2, b1, superjet, and just sold my sxr, had a gp1200. The superjet is my favorite, and if i had to pick one, it would be my superjet hands down. However, i have a lot of time , money and parts in my x2, and while i consider getting rid of skis, the x2 is something i doubt i will ever part with. Its like the old car in my garage that i like to tinker with and take to shows, but i have something else i use on the regular.