I would say for what you will be using a meter for, the extra cost for that type of meter is not worth the cost. I have two meters I use. Both are auto ranging. Not sure even that is worth the money when we usually are measuring 18 volts. I noticed that Sears is advertising a nice meter for what we need on sale for $13.00. that should get you through shooting trouble on a layout. Maybe just maybe you might want a meter that reads AC Amps but I have yet to use that feature shooting layout problems.
A true RMS meter is needed only when accurate measurement of non-pure sine wave AC Voltage is what is sought. All of Lionel's classic transformers from the pre and postwar era are pure sine wave. For amp readings, true RMS is not a significant factor. I use an inline series meter as the doughnut clamp style ones require an external power supply of sorts.
I vote for true RMS. Realize that the true heating power is only known when you know the true RMS. The true RMS AC voltage yields the same power to a resistor, a bulb, or smoke unit that a DC voltage would. I bought a true RMS Fluke meter 25 years ago which still works fine for me. Just a few dollars a year so far.
You can pick up decent true-RMS meters for not a lot of money, so there's no real reason not to have the capability.
eBay: 352143983181, $4 shipped
Gunrunner, I rarely if ever find fault with your answers/comments, but on this one, what is the sense? I have two expensive meters but I and probably most of us don't do the work you do. But when I do a reading and it reads 17or 18 volts I am happy. If I a gain go out to the block in question and again read 17 or 18 volts I am happy. If I am down to 10 volts I begin shaking my head. If I read zero I put my meter on the ohms and begin looking for opens or shorts where they shouldn't be. This all works fine for most of our trouble shooting. Let's remember why we are all here to begin with. To run trains and a new locomotive or rolling stock is better than buying an expensive meter that is accurate to one thousands of a volt.
Its an easier way to read the voltage output of those **** CW-80 transformers
Theres a handy conversion chart that one could use with a "non rms" meter on this thread: https://ogrforum.ogaugerr.com/topic/cw-80-voltage
Johns tip of the $4 is great. I perused for an RMS meter ( for my **** CW-80 transformers that I use for accessory power) and found them starting well above $50.
I still think one day I will just add a second 180w brick for my accessories and free myself of two **** CW-80s and the oddities that go with them.l I.E true RMS voltage meter requirement, pulsating power on the throttle side, high voltage reading at zero, noisy fans (of course)..... etc, etc.
Lionels most common starter set transformer was engineered by Dr. Frankenstein.
Gunrunner, I rarely if ever find fault with your answers/comments, but on this one, what is the sense? I have two expensive meters but I and probably most of us don't do the work you do.
Well, if you don't see the need in your situation, there apparently is no sense. I was simply answering the question of cost of having a meter with true-RMS capability. It's simply a bit more accurate in more situations, but it's not life or death working on model trains.