The stock Samurai T-case shifter leaves the front and rear driveshafts connected through the transfer case when in "neutral". When flat-towing, the rear driveshaft then spins the front driveshaft at highway speeds, which it was never intended to do, and it's easy to break something expensive. Twin sticks allow you to select 2WD and Neutral at the same time -- a "True" neutral for towing. This is especially important on a lifted/modified vehicle with more extreme driveshaft angles. You still have to run the engine to spin the gears and lube the seals every 200 miles or so. I've installed twin sticks for towing my Sami behind a motorhome, 'cause I can't be dropping the rear driveshaft every day of a 3-month, 10,000 mile summer trip. I installed the twins sticks with 4.16 gears 'cause you'll need to remove the center interlock shifter ball. I run the engine in gear, every 200 miles and/or when gassing-up, to re-lube the internals just like Suzuki recommends, starting on page 8-6 of my owners manual.
This is a fairly popular subject and there's been much discussion, here and elsewhere. Some searching will reveal a bunch of additional information, but you'll have to separate fact from opinion and conjecture. Besides the Evil Twin (my choice), Rock4X Fab also makes a very nice set with a modified Jeep (dare I say that word?) lower boot, absent on the Evil Twin. You'll always have to bend the sticks yourself, and some welding or heat may be required. I really like mine, for what they do for me and in my situation.