My buddy has built and flown both..

One is scale (ish) the other is a purpose designed 'fun flying' airplane.

The RV4 is a great plane, and modeled after the popular RV4 homebuild. But is heavier and flyes a little faster than the SE.

The SE is 'very loosely' based on the Extra 300, but as mentined, is purposely built as a 40 sized aerobatic plane. (And everyone will attest, it is a blast to fly!!) Builds light, and is a ver simple / easy build. The RV4 take much longer to build, and has some 'interseting' buiding techniques (does require soem building skills).. The RV4 has a larger overall fuse.

The RV4 is a full length wing, with plastic tips. The SE is a two peice wing, so transporting is easier. The RV 4 with flaps, requires 4 servos in the wing! The SE only two. The SE is a symmetrical wing, while the RV4 is semi-symetrical.

The SE is all laser cut, while teh RV4 is die cut..

The RV4 has a cowl, and requires a Pitts / Slimline style muffler to fit in the cowl, and is moutned sideways. The SE is a typical 'open nose' with a traditionally moutned engine. But teh SE does have a tight radio compartment. The SE has an ample hatch wher teh cockpit is, so it is easy to work on / in, but tight.

The MDS 48 on the SE really pulls it around teh sky. The same engine on the RV4, it shows it could use a little more juice.. It is, afterall, slightly heavier, and more surface area (more drag)

So, it really depends on what type of flying you want to do. The SE will do all sorts of flying, including 'backwards' on windy days. The RV 4 is scale, and should be flown as such. Either way, you can't loose with either plane!