Recently found and reading through with interest of the H520 & mapping. Within the thread discussion the S900 with X5 was mentioned and is correct, and the X5 isn't an ideal camera all around in comparison to the X5R. Originally I thought they were similar, but multiple tests by various examiners have clearly show the X5R superior in sensor, ev range and sharpness, not including the RAW video abilities separate from this discussion.
What caught my eye were a few comments on the S900 with the X4S & X5S. The X4S & X5S are not compatible with S900/S1000 A3/LB2 builds and are compatible only with I2 and M200 series platform. When the S900 or S1000 is converted & upgraded to the A3Pro/LB2 electronics, it essentially mimics the M600Pro's electronics and available gimbals & cameras. These would be the X3, Z3, X5, X5R, Z30 and XT Thermo, and RoninMX with the one exception (limited by FW only for market reasons) is the XT2 Thermo accepted on the M600Pro and not S900/S1000 A3/LB2 builds.
Along that subject, the X4S is superior to the X5S for geo mapping images due to the shutter design. The X5S is a higher quality camera more cinema focused and video footage and isn't ideal without the I2 RAW components for cinema. The S900 / S1000 with the X5R provides better images than the X5, and a RoninMX with A7Riii native 42meg Full Frame would be the highest detail and image quality currently available on the platforms.
I do look forward to the progression of 3rd party programs that are now including the H520, in the last 6 months there have been a few adding the H520 to the supported platforms. That is promising news for the H520 and it's cameras. It hasn't moved forward much internally but it is beginning to pickup 3rd party attention which in my opinion is better in the long run gaining 3rd party support.
I agree about the X5, im not a big fan of it, the quality isnt that good, focus is also a big pain in the behind. X5R is the way forward if sticking with this spec, but im currently manufacturing a gimabl unit that will carry my bigger Canon DSLR, the looking to use our works A7Riii with that too, all being controlled by Intelli-G and third party Gimbal controller.
The advantage of the X5 etc is the weight is very low, even with an S900 its a consideration.
I wouldnt use this set up for surveying, the 520 is currently more than good enough for the jobs we have been offered, my original thought was to try the S900 for a few maps, but after getting to grips with the 520 there seems very little point.
But on the up side, im getting to grips with using the N3+, LB2 and finding work arounds for the camera and gimbal issues, control is divine, its floats like a butterfly, its incredible, but can no way match the 520 for ease of mapping. two tools, different jobs i guess.