KJW m700

I'd personally forget that barrel, and buy a decent VSR barrel because the wonderful thing about KJW M700's is that they can take VSR barrels and buckings without needing to buy a conversion chamber like the Tanaka needs.
King Arms airseal bucking for VSR works really well on the KJW, I use it in combination with a deepfire 6.02 barrel with excellent results, though I do use my Tanaka PCS bolt instead of the stock KJW bolt.
KJW long and short mags fit in Tanaka rifles, and Tanaka short mags fit in KJW rifles, but I don't have a Tanaka long mag so I can't say for sure but it makes sense that it would. Just get the KJW long mags, they're exactly the same but a bit cheaper.
You might need to fit an O-ring to the silencer adaptor, because the barrel dimensions are slightly different to the Tanaka, but I've got an adaptor on the way to me so I'll be able to verify that in a day or two hopefully.

The hop up on the takedown is much easier to access for work and maintenance, and there's not any wobble in it. I own one myself, and I wouldn't recommend not getting it

I've not had a problem with mine that I couldn't fix, the stock hop up bucking was rubbish though. I'm using a King Arms Airseal rubber, and a H-nub and I'm getting some really good results. You can also get a regular M700 hop wheel and modify the receiver to allow you to use it in the takedown version, all that needs to be done is one hole drilled, which is nice and easy