Even with 4 inches of lift your going to want to do the SYE. it should be done after 3 inches to help the drive shaft angles during flex. At certain points during your jeeps flex it will bind up your drive shaft and literally rip your yokes apart. Broken u-joints and shoulder straps will be your bane till you rip a yoke on some trail.
Having driven both kits, I.E. a 4 inch spring lift with factory arms (in a 97 TJ ) and mine a Tera-flex 4 inch long arm kit I would have to say go with a long arm kit if at all passable.
Try this little experiment: take a basketball, and with your arm at 45 degrees bounce it as hard as you can not flexing your arm. The jolt you feel in your shoulder is what your going to feel in your jeep with a short arm lift kit at 4 inches.
Now take your whole arm and lay it out to about 15 degrees ( almost parallel with the ground ) and bounce the basketball. Big difference here.
I.E. the longer the upper and lower control arms will absorb any road shock and transfer less of it through the long arms to the frame and tub of your jeep.
Long arm kits also help going through things like pot holes, tuned and un-tuned road ripples, small to medium size rocky roads by transferring less of the road vibrations through the long arms thus making the springs and shocks take up the load. Similar to a factory short arm with no lift.
This technology was developed by the S.C.O.R.E. racing teams to help them take bumps and jumps at a higher speed than shorter factory designed suspensions.
The best way for you to know is to ask your jeep friends with lift kits on there jeeps and find two with both a short arm and a long arm and do a side by side comparison, you will find the long arm rides better than a factory suspension.
Now about body lift:
Body lifts are a big no-no in the rock crawling scene. Every U.R.O.C. buggy you see is as low to the ground as passable. The taller it is the easier it is to roll. Yes it is the cheapest way to lift a jeep but your only gaining upper suspension compression clearance. I.E. your tires not hitting the tub when you compress one side of your suspension. Why not add 6 inch springs instead of 4 inch and adding 2 inches of body lift? With longer springs you gain that extra two inches in suspension travel, where you really want it.
Any time you lift a jeep you loose tilt angle ( I.E. how far your jeep can lean on an angle ). It is always better to have that extra 2 inches in suspension travel than in a non-flexible body lift. What your trying to do is to keep the frame and your tub of your jeep closer to riding level than having your suspension bottom out on your bump stops and tilting it to get through a off camber situation.
What it comes down to is cost. If you cant afford to do it all at once buy it piece meal like buying the lower arms and a SYE for a 4 inch lift. Then later on buy the upper control arms and bigger springs for a 6 inch lift and sell your 4 inch springs on E-bay. New 6 inch springs will run you 250$ from Rock Krawler. You can sell your 4 inch coils for 40-60$ a piece on e-bay all day long. So you loose a few few bucks later on but you wont regret it once your rig rides like a caddy with 6 inches of lift.
