The cost will be around $100 to upgrade. For that you get a number of incremental improvements:
- Wider 10mm belts rather than 6mm belts
- Stiffer core
- Closer mounting that has the spindle less cantilevered
- Built-in belt tightening system
- More adjustments for squareness
I’ve never seen a head-to-head comparison with identical machines comparing the Burly to the Primo. Ryan promoted a drag race in this topic that has some impressive numbers, though the machines might not be “stock.”
I would expect that the more your cutting stresses the machine, the more improvement you would see from a Primo. That is, you might get little benefit from cutting softer woods, but the Primo might shine by comparison cutting hardwood and aluminum. I upgraded, but I typically don’t push my machine, and I don’t remember my Burly settings to compare. And like David, I upgraded to stainless steel at the same time, which gave the machine a significantly better feel.