How important is the tonearm?

Actually, the mass of the arm has very little if any effect on groove wear and designers do not attempt to keep it as low as possible. The mass of todays arms is higher than it was in the 70s in general. Something like the Transcripters VESTIGIAL arm with its mass of 3 grams or less would be laughed at today. The SME 3 arm had a mass of something like 4.5 grams, the 5 is 12 or 13. Low compliance cartridges will not work well in low mass arms in general. The critical factor in groove wear is the shape and polish on the stylus. Long ago there was an experiment in which an LP was played several hundred times tracking at 3.5 grams with a high quality stylus; there was no wear when it was examined under a microscope. Badly polished styluses with irregular shape are the most danger to grooves. I remember it the 70s HIFI News had a cover showing the magnified stylus of a group of top cartridges; many were obviously misshapen. I don't know what todays would look like; better I hope, given current prices.

Scipo said

... most designers try to keep The tonearm's mass has low as possible to avoid unnecessary wear on the grooves.

I do not agree with that statement. What does tonearm mass have to do with tracking force, in and of itself? Tonearm mass is a the main determinant of resonance. Is there a difference in groove wear if the same cartridge was mounted on a Grace 707 at 7g and an Origin Live Silver at 14g, assuming that both were adjusted for 2g or tracking force?

The job of the tonearm is to hold the cartridge in the groove with the grip and determination of The Incredible Hulk while maintaining the finesse of Tinkerbell.

That table deserves either the Triplanar or Graham. My personal preference would be for the Triplanar. TTweights also has the Talea, which is expensive, but will leave you speechless, even with a "lowly" 103r. You should try to hear one even if you have no intention of buying it.

(fill in your own TV voice talking really fast for this last part)
disclaimers: I also sell Taleas, but have no association with TTweights, other than we both sell that arm. I've owned a Graham 2.2 in the past. I currently own and use a Triplanar along with a Talea. I don't have any association with Wheaton or Graham.

Well I'm going to be the odd one out here.
To me it's the cartridge that determines the sound which comes from the vinyl groove.
I've got 8 arms and 16 cartridges and most of those cartridges will sound their best in many of the arms (value from $460 to $10,000).
It's really only if you want one arm to go with many cartridges that the arm cost may (and it's a big may), equate to a more universal application...ie high compliance MM/MI and low compliance MC?

But many of the high-end current high-mass arms do NOT sound well with high compliance MM/MI cartridges.
If you believe that only low compliance MC cartridges qualify for the high-end, you are deluding yourself.

Very. SME, in my opinion makes the best arms, but pricey. However setup support is excellent. Overall I am a fan of VPI, in terms of sound delivered, value and support it is hard to beat. The dealers are very knowledgeable and Harry goes the extra length to support his products. Great efforts are made to integrate the arm,table and cartridge at the factory, providing less hassle that you get with other arms when trying to marry them to other tables. It leaves you more time to enjoy the music, and not be fussy with the gear.