What kind of folding bicycle should I buy?

Here's the issue...I already have a dahon curve d3 which i like a lot and since i live in phoenix arizona only having a 3spd hub gear isnt an issue for commuting due to everything being flat here in the city. now im looking into a folding bike for more of a multipurpose bike, using it more for touring and recreational riding, but still using it for commuting if need be. my options that ive narrowed it down to so far are the downtube 8FH, xootr swift, and a brompton. for the brompton it would be either the m6r or the s6r. here are my reasons for considering each. the downtube 8FH from what ive read is an outstanding bike for the price. the full suspension makes it especially suitable for light mountain biking and possibly even some light touring if the proper racks were added. while a little heavy for its size the features and the price more than make up for it in my opinion. the swift is another option because it is famed to have the ride of a real bike which is important because i would be using it for the same reasons as the downtube. i know the folded size of the swift makes it a bit impractical for multimodal commuting so if i were to get the swift it would most likely be a noncommuting bike and i would stick with the curve for that purpose. now the third option is the brompton. i havent decided yet if i want to go with the s type bars or the m type bars. while the s type bars look cooler and are more suited for longer riding i could easily attach some stubby bar ends to the m bars(which looks pretty cool as well in my opinion) and have the option for both an upright riding position and a lower, stretched out riding position. now i know that a factory brompton has limitations when it comes to touring and longer riding so if i were to go that route i would be spending extra money to outfit it with a mountain drive to give it more gearing options, as well getting a brooks saddle and better pedals. if i were to go the super brompton route then it would be my only bike and i would be selling the curve. anybody have experience with a modified brompton to be able to attest to its long distance riding abilities? or would it be better to go with the swift or downtube to use for longer rides and continue to use the curve for commuting? any folding bikes im leaving out of this that i should be including?

1. I have a Xootr Swift and am quite happy with it since it does ride very closely to a regular bike. I used to have a Dahon for multimodal commuting since it folded compactly but I wasn’t all that happy with the ride. I’ve ridden a Brompton and if you can afford it, it would probably suit all your needs. Personally, I found the price too high. I’ve never ridden a downtube so I can’t help you there but they are certainly more affordable than most folding bikes. A folding bike buyer’s guide I found (listed as a source below) helped me make a buying decision, it lists some other folding bikes for you to consider as well.

2. Where I live, a neightbour used to have a folding 26 or 28-inch gentleman bike

   That should be versatile enough to do all that you described, commuting, light mountain biking, touring, and perhaps single gear racing, too

3. Why not keep the curve for it’s intended purpose and get a regular bike for touring or trail riding.

4. Brompton makes an excellent bike that is a fantastic commuter & general purpose bike. I cannot say it is superior to your other choices. I find it odd you want multiple specialized folding bikes. I consider folding bikes to "specialize" in folding. They are always a compromise in weight/price/performance. Owning a folding bike is great but are you are in situations where you need to tour long distances AND the bike needs to fold up AND you do this so often your existing folding bike is not specialized enough to make you happy? After all, you even claim one of these bike don’t fold down enough or your multimodal commute.