When compared to a decent DMM, they do exhibit many drawbacks, but as many of us love to restore the older test equipment as well as in my case audio equipment, many of these service charts/manuals actually quote what service tools are required in order to test the equipment and quite frankly a modern DMM with its input impedance being in the realms of at least 10Mohms and in some cases even into Gigohms then the voltages referenced in manuals become useless, and then you are into another rabbit hole calculating what the actual voltage should be reading with that meter rather than the required 20,000opv meter.
Therefore, IMV, if you're serious about the repair / restoration, then you do need to have at least one such meter in your collection. Allowing these meters to fall into the hands of the "Steampunk" brigade is much a cardinal sin as the hallow tube rapists of old scopes etc.
I've run into this a number of times in service literature where measurements are specified using a VOM with a stated Ohms per volt rating or, quite often, VTVM in which case a DMM will be fine. The other given condition for measurements I've seen is a specification where the measurements shown were taken at a given line voltage. Here, 117, 115, or 110 volts comes up in vintage documents quite often but line voltage standards have crept up over time.
I think the nominal electrical code specification is now 125 volts which is considerably higher than what was coming out of wall sockets when nominal 110 volt equipment was designed and the 128 volt winter season voltages I measured at my house is even higher so a variac to adjust the line voltage so it's approximately period correct or meets a service manual specification is quite often needed in addition to a meter with the correct loading factor.
I have an Agilent U1272A that has the Low Z voltage function but I've never actually used that; it would be interesting to try that out and see how well it could substitute for a Simpson 260, Triplett 630, AVO-type meter.
The Micronta FET meters are absolutely underrated gems of meters. Decent basic accuracy and flat impedance. Not expensive and surprisingly difficult to fuck up.
I see them as closer to an HP 427A than a Simpson 260.
I've thought about getting a Micronta FET meter in order to combine analog display with DMM light loading but I can't overcome the whole Radio Shack stigma. And I have the two 427A sitting on the shelf already that I'm still meaning to take down and get to along with those two retired lab PCs I've never fired up. I might get to that this weekend since I struck a few other items off the list yesterday evening.