I need an advise from experienced flyer. Im flying Cinestar8 regular version with MikroKopter( Flight-Ctrl V2.1, Navi-Ctrl V2.0, Gps, BL-Ctrl V2), QuadroPower Motors QC-3328, 2 x 4S 5800 batteries (in parallel), lifting brushless gimbal with Panasonic GH4, and get around 7minutes of flight time. I ordered Movi M15 with wedge, multirotor adapter, Movi control, connex hd link and planing on lifting RED Dragon with primes and later Alexa Mini. Is it enough upgrade on craft to go with HL (550mm boom) x8 ? Do I have to upgrade something else?
If you convert your flat 8 to an X8, you're actually going to lose quite a bit of power! In order to substantially upgrade your lift capacity, you're going to have to swap out almost everything. You'll need to move to 6S batteries instead of your 4S batteries When you do that, you'll have to get a new Flight Control and BLs and power distribution board And then you'll need larger motors And then you'll need larger props So basically the only thing that'll be left is your frame. You might want to consider working with somebody like Kopterworx (assuming you're in the EU) or Quadrocopter (if you're in the US) to spec out a new copter. You could also look at the new Freefly ALTA, which might be a better investment than building a completely custom copter.
Just to amplify what Steve said, mounting two motors on a boom coaxially (as one does for the X8), results in a 20-30% typical loss of overall net thrust because the lower propeller is operating in the turbulent high speed air produced by the upper propeller. Andy.