I've had a couple & there's a reason they're still popular after being discontinued 30 years ago.
Just a really nice power to weight ratio in a mid size engine, decent handling, great gas mileage.
Like almost every bike on the planet, someone will complain about the RPMs
being to high at freeway speed. If that's an issue a simple sprocket change will make a difference but don't expect it to sound like a Road Glide with a 6 speed in high gear. In stock form they have enough torque to get a 200 pounder around without too much complaining.
The only consistent issue with the engine is the clutch shaft seal on the left side of the engine. They eventually all leak but it's an easy fix. The original design requires you to split the case to replace it (PITA and I don't mean the 'organization'
. You can chamfer the outside edge of the seal after popping out the seal and grease it up to push the new seal in from the outside. There are tutorials online for this.
I sold my completely restored 82 XS650 Heritage Special a couple years ago but still have my 77 hardtail. The 77 is still in the ingredient stage since it spent the last couple years in storage after my divorce but now that I have my own place again I'll resume screwing around with it.
I may even finish it some day.
TC Bros is probably the best place to get bobber parts, great selection & very decent prices. Good guys to work with too & they answer questions quickly. I've never heard anyone complain about them either, that's fairly rare in the custom bike parts business, especially when they specialize in parts for discontinued models.