What benefits to expect from tonearm upgrade

Thanks for all of the insights,
How about if I rephrase my question..... Theoritically.... What audible improvement to be expexted from moving from an "okay" tonearm to an "excellent" tonearm.

Jperry has mentioned imaging, does it mean better "placement of instruments" or bigger soundstage? Is there any other else?

Please when somebody mentions in technical/measurement terms, what will be the audible impact of that better technical/measurement.

Thanks again

I found that tonearm improvement - even with the very best arms are not dramatic...better tracking, cleaner, clearer presentation, etc.. differences that will make you smile, not jump for joy.

Without the right tonearm you will never realize the potential of your cartridge or turntable. Unless both are very subpar, get the great tonearm first.

I have set up my system very carefully and that is why I commended as I did.An SME V didn't do it when I was experimenting,as well as other tonearms.When I "tuned" the sme's mass to match that of the rb300 and my cartridges, well, yes the V sounded closer to the rb and for me not worth the extra cost.A tonearm in itself does not sound good or bad,it is the good pairing with a cartridge that does the trick for me,as well as the phono preamp as I said earlier.
By these comments,I must say I do not underestimate any tonearm's qualities , low or high cost.

I agree with you Kiddman.

Gondo101, my experience was that images resolved into individual instruments, and there was no smearing. It was easy to follow the musical line from individual instruments. The difference between the Basis modified Rega arm and the Basis Vector arm on my Basis 2000 turntable, using a Shelter 901 cartridge was immediately noticeable and very significant. I was stunned because I did not think it would make a huge difference, but it did.