I thought I would share my considerable research on the subject. My research was focused on the $1000 and less category.
While several manufacturers have bikes that have weight limits of 220-230bls( Dahon, etc). There are basically two choices for a clyde.(note I do not include full size foldups )
The Downtube FS (245lbs, rated) downtube.com $369 on sale$479 normally, one year warranty parts frame
Xootr Swift, xootr.com, (260lbs rated, $699, one year warranty parts, lifetime frame.
Some of the over $1000 manufacturers, will do customs builds for heavier riders...if anyone knows what their weight limits are(if over 260lbs) please post.
Both companies have excellent reputations. Xootr is about 4 lbs lighter. The ride of the Xootr is supposed to be EXCELLENT while the ride of the FS is good-very good. Business week rated the swift the best long distance commuter. You can find logs of people pimping the swift out for touring/racing. The frame of the Xootr is considerably stronger/stiffer than the FS per the forums.
The FS has a smaller fold yet the Swift breaks down in 15 minutes into a standard 30 in hard shell suitcase. My concern with the FS vs the Swift was how big was the cross sectional fold. While the FS gets smaller it sticks out more sideways. So with the add on fold up pedals, the swift is great to lean against a wall (e.g. in a theater, elevator)or narrow space. Since I am in NYC, I expect to fold my bike often in the day...and the fold on the Swift is 15 seconds vs 45 sec on FS Not much of a difference...but if you are doing it 10 times in a day...it can be(time/hassle). The height of the Swift folded is a nice height so you don't have to bend down...just lean a little and pick it up. The frame shape of the swift is ergonomic to your hand. I suspect the Swift is easier to carry over a distance due to fold and definitely 3-4 lbs lighter.
I had a hard time deciding which one to get.....considering the price difference as I was only going to use it for 3 mile max rides. But the test ride of the Xootr was amazing and everything that everyone in the forum spoke of. Yet, $330 difference.....would it be worth it since my rides would be short commutes. I made my decision after speaking with Steve at Xootr about their frames and being a bigger rider. He said out of the 1000s sold they have only had 4 fail...a problem since fixed and one by a rider who admitted to not inserting seat tube to the minimum depth. When a frame fails, they send you a brand new bike. You put the old one in the box, ship it back and you keep the new bike. LIFETIME WARRANTY on frame is what I kept thinking
Also, I thought that if the ride of the Xootr proved good enough(so far it is...have to put the clipless on and go do 30-40 miles) it may become my only bike until/if I get back into racing or mtn biking again(since moving to NYC from SF, it is such a pain to go riding). After riding the Swift for a week, this is QUITE likely. The ride is that good.
With service like that(ship replacement bike)....and I had tried their Scooter(Roma) which was solidly built(300lb rated)...downhills at 25 mph jumped a couple of curbs (due to a to0 fast of a downhill...the brakes are good but I am a 260lb clyde). Since I was upgrading Steve didn't even charge my shipping on the Scooter which is normal on returns.
I am in the middle of doing a 30 day evaluation. Doubt seriously I will return it as I love it and get compliments all the time. The Xootr is the coolest foldup besides the very non standard bike parts GoBike(245lbs rated) which is very difficult to get and one wonders how long they will be in business considering how their marketing is lacking(research the history/biz development of the company).
Concerns: I am 6'4", 34 inseam and I got the XL size. The seat post is right at the height where I may go with the XXL. Unless I wanted my bike in a racing configuration(lower handle bars without drop handlebars) I would want to get the longer handlebar stem as I am bent over. The seat is a good 3-4 above the handlebars.
Swift Recommendations: Don't get the fenders that they offer, there are some after market clip ons that are recommended in the other forum. Have to dig up that link. Also, folding pedals are nice addition(don't hit yourself others when pushing/carrying it). Unless you are doing mtn riding or long distance, pass on the Thudbuster on initial purchase. Although highly rated, the ride of the Xootr is pretty amazing as is and you can always buy it later.
I will post a full review of the Xootr after I have really put it through it's paces. It was very easy to put together.