Usually as the price goes up, they get closer and closer
Try several $1600 fluke bench multimeters such as a 8846A/SU and I can assure you they will all measure near identical under all conditions.
All of this isn't relevant to the A though. Any cheap meter on the market is plenty accurate for working on the A. There is not a single part on the A that cares whether it is running on 6V or 8V or anything in between. As long as you make all of your measurements with the same meter its not going to matter if its off some.
You also don't care if your ohm meter is off by 1-5 ohms. If you short the leads together and see 3 ohms, you know anything measuring around 3 ohms is a good connection.