No hard & fast rule, but developing JK wisdom seems to be that when you reach 4" you're at the point where a long arm starts to become a benefit. At 5 - 6" you get the payoff. I'd say with your setup and future plan a long arms becomes very desireable. Some good choices out there, varying between conventional 8 arm to the Rubicon Express / Clayton radius arm style. In every case a lot of cutting & grinding required to get the old brackets off.
I just had my TF 4" upgraded to long arms. Farmed it out to High Country in Denver, just wasn't something I felt confident in doing myself. Haven't had a chance to get it on the rocks to compare. However, what I can tell from just flexing it out on some local "test rocks" is that it hooks up faster and with less drama. Street ride quality and stability are noticeably improved. Moab this week, so I'll be better able to judge.
'09 JKRU. 4" Teraflex long arm, Teraflex R44 housing, Teraflex / Fox Resis, Poly Performance skids, Nemesis Billy Rockers, Nemesis flares, 37" ATZ P3s on 17" 5x5.5" Trailready HDs, Spyntec hubs, Teraflex BBK, Mopar BBK master/booster, Superior front & Alloy USA rear axle shafts, CTMs, Reids, Synergy drag link & tie rod, WTOR hydro-boosted steering, 5.38s, TF Dual Rate front bar, TF bumpers, Warn Powerplant, Tom Woods shafts, AA xfer case cable, Kilby canister relo, RH4x4 cage.
Last edited by SoK66; 04-03-2013 at 07:35 PM.