AEV uses your existing JK for the swap, either a new one you provide of one you already own. To be clear, they use new Hemi engines.
Performance wise the 5.7 VVT Hemi has everything you could ask for from tons of torque to fantastic street and highway performance. The only shortcoming I have found is range. A Hemi swap should include a Genright or LongRanger/ARB auxiliary tank. Either one almost double range.
Without the auxiliary range is between 275 and 325 miles on the road depending on mix. If you were to travel a full tank off road I suspect the range would be about the same given the JK's brick like aerodynamics and the way the Hemi loafs - with plenty of torque - at lower RPM's.
I have a LongRanger on order. Adds 18.6 gals to the 20.6 factory tankage.
JPK