Different arm for VPI Scoutmaster

Not the SME as it would require cutting the base. Something like the Jelco 250 or 750 would probably be relatively easy, as would some other arms. From my experiences with a Scoutmaster [I am a VPI dealer] the original arm is a good match; unless I had a compelling reason I would either leave it as is or start with another table-arm combination. But if you are set on it it it would not be too difficult for most conventional arms of around the same length. Check the chart on Vinyl Engine for arm length and make sure the arm base fits the table cut out.

Why would you want to do that??

Actually, I called VPI and they said that I can trade in my JMW9 for a new JMW10.5. Is it worth the upgrade?

I should know this but while I had the 9" arm on my Scout and Scoutmaster and the 10.5" on my Classic there was a gap of several months between having them set up. Even though I am a dealer the exchange cost is not on the price sheet; I feel the 10.5 is the better arm but not knowing how much money is involved I am loath to give advice.