to volume pot or not to volume pot

the volume is going to add a layer of stuff between you and the music. If you are never going to use it, don't get it. (If you might try it direct, with no pre... then it might be a worthwhile investment.)
PS the theory is what is going on in the recommendation you read. Sometimes theories do not hold up in practice....

If there's an audible difference between the volume model and the standard model, I'll give you a Golden Ears award. There's obviously more "stuff" in the volume model, but it amounts to an extra inch of wire and a potentiometer. If you plan to use the volume control, get that model. If not, get the standard unit.

The volume model gives you the opportunity to eliminate your preamp, but I doubt that will give the best results. Are you familiar with passive preamps? That's what the 834P volume becomes in this situation. In theory, it seems smart to reduce the number of components in the signal path, but an active preamp does something the 834P doesn't do. It controls the impedance of the signal running through the cable and keeps it stable. Passive preamps are notorious for sounding thin in the bass and mid bass because they can't control these impedance fluctuations. It's best to hear these things first-hand rather than from some stranger. If you have the opportunity to listen to a passive preamp, you should do so before deciding on the 834P.

If you want versatility down the road,I'd go for it.

Won't the volume pot function as an adjustable gain ? This might be convenient!!

"The EAR's voltage gain measured 49.2dB moving-magnet, 68.2dB moving-coil. These are very high values, particularly for the MM; typically, the gain in MM gain stages is 35–40dB, and 55–65dB in MCs. I don't anticipate this high gain to cause any problems, but I'd check to make sure that it won't overload my line preamp"----Thomas J. Norton

If you can't hear the difference with a pot and an extra inch of wire in the path then maybe your system/ears are not very resolving.

Having said that the flexibility of having the volume pot still may be well worth the price. Having the option of running direct is very compelling.

Most of the negative impact of inserting the volume pot can be avoided by setting the control at the maximum position. At the maximum setting it is more like a switch contact than a pot.