You need to be familiar with the angle of view of the meter, and to be able to tell what the meter is actually seeing.
You can then look at that portion of the scene, and evaluate for yourself how much the average reflectance of that portion deviates from a middle/18% grey.
In essence, I look at the scene and say to myself something like: "that looks to average out at about two stops/zones brighter than a middle grey. So I better take a reading and then open up two stops."
I prefer to use incident metering.
“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”
Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2
With a spot meter you should be setting out to examine the luminance of critical parts of the subject and not assume it is overall an "average" scene of Zone V from a singular reference point The method you stated :
When I'm feeling lazy, I just pick what I want it to be zone V and meter THAT using spot. Most times, I use it incident if I can get to the subject.
is the incorrect use of a spot meter. Examine the entire scene and let the meter determine the SBR and thus the resultant exposure.
It makes no difference on the camera, certainly not panoramic. Nor strictly does the field of view of the lens. The viewfinder will determine the limits (edge) of metering. But you will be doing more metering for that given (panorama) format. I have done this with my own 6x17cm so I speak from experience.
I don't see how your situation will be improved any by shifting away from the flagship 758.
When metering NON-SPOT reflective, I am aware the meter has certain degree of "field of view" and meters that area. If it has an unusually bright spot or dark spot, it'll all be averaged. Also, the field of view of the meter does not usually match that of the lens, meaning two are looking at different area. Now, how is this accurate?? (or is it not supposed to be precise?) It is a particular concern to me at this point because I am going to get a panoramic cameras and I know they will be looking at vastly different area than the meter..
I don't really see how a panorama camera will make things more difficult with metering — any type of metering. And I speak from experience with a 6x17cm.
"Field of view" of the meter is not relevant. What and where (and how) you meter has weight. You will only be metering those elements / subjects that you are see through the (pano) viewfinder, which will be reasonably well matched to the angle of coverage of the lens. If there are very dark and very light areas in the image you can take a gamble (as you are wont to do) and think they'll be averaged with incident or reflective based on a grey card (even if your meter's memory function is usefully employed in additive mode) but the scene is actually crying out for spot metering — a method that delivers excellent results when used correctly.