what he ^^^ said, deffo go with a custom built re-map makes sure they dyno the disco before and after these "we come to you" lads just dump a generic file on your ECU and vanish.
If you are referring to Mike at Dynachip that is wholely untrue and bordering on actionable.
Speaking from personal experience, Mike did a first class bespoke job on my car. Of course he started with a standard map and reconfigured - that's what they all do. You don't seriously think that some tuner out there actualy wrights totally individual maps for each car they tune do you?
He started with a little state of tune, then we road-tested and he tuned some more, then another road test and he refined it. He was very much committed to giving me the driving experience that I was looking for and wouldn't leave until I was happy. That vehicle was run by me for approx 30,000kms AFTER remapping without even a hint of trouble, but loads of driving pleasure.
And as for rolling road testing, it seems to me that it gives statistics to provide bragging rights at the bar, but not much else.
Mike has been doing this work for nearly 10yrs now with conventional tuning before that, so he certainly is not a fly-by-nighter. For me the other big advantage he has is that he does loads of makes/models of vehicles, not just Land Rover, giving him a breadth of exposure and experience that a one-make operation could never hope to have.
He also competes with LR products himself.