Long arms are not "better" than short arms, this is just a common myth that's been perpetuated all across the internet, likely due to very, very deceptive marketing tactics from shady companies.
The reality is that short arms have their shortcomings, but long arms do as well. For a Jeep that is lifted 4" (the typical lift height) with the stock wheelbase, short arms would be better than long arms.
The ideal setup is usually a mid-arm lift, which falls between a short arm and a long arm. Of course the issue with mid-arms is that they aren't going to be bolt-on, it will require lots of cutting and welding. In fact, it's safe to say that if you're very, very serious about wheeling, there is no such thing as an ideal "bolt-on" lift.
That's not to say that a 4" short arm lift can't take you a long ways (it can for almost everyone on this forum). But if you're doing some serious, hardcore wheeling, any of the bolt-on stuff is simply not going to cut it.
Anyways, as to coilovers with a short arm lift.
First, you won't be able to fit coilovers very easily on stock width axles, so in order to run them with any success, you're going to need some wider, aftermarket axles.
In addition, are you away are of what kind of work it takes to fit coilovers? A LOT OF WORK.
I looked into this heavily before I did my Savvy mid-arm lift, and it's no joke... it takes way more work than it's worth.
If you talk to any of the experts on this forum, you'll they'll all agree that coilovers are more effort than it's worth, unless the build really dictates it. For instance, if you were installing crate axles (i.e. Currie RockJocks) with no provisions for the stock coil springs and shocks, it would make more sense probably at that point to put in coilovers since you'd already be doing a considerable amount of work anyways.
But on a TJ with stock axles, it's a waste of time.
If you're installing those aftermarket axles you'd be running with coilovers, you wouldn't be using short arms at that point most likely.
I'd also like to add that the term "long arm" is relative. Even a "mid-arm" is longer than the factory short arm, so by definition it is technically a "long arm". I think the companies like Savvy who make a mid-arm have just resorted to using the term "mid-arm", since it falls between the length of a factory short arm, and all of the other aftermarket "long arm" lifts on the market. Therefore the name is very fitting.
I guess what I am trying to get at is that every single "bolt-on" long arm kit on the market is not going to be "better" than a short arm.
One of the more knowledgeable folks will come along in a bit and explain how much work coilovers are and why you'd seldom see them with short arms.
@toximus comes to mind.
