Sold several expensive guitars the past years on Reverb and eBay, no major problem so far.
I make it clear the guitars are sold as described and returns aren't possible. That gets rid of buyers who buy/return just for the sake of trying guitars, I'd rather let those abuse the overly generous return policies of Guitar Center/Sweetwater/etc than waste my time/money.
But there are unscrupulous buyers and sellers.
I had one claiming the speaker cabinet I hand made got severely dinged in shipping, many days after delivery.
I gave the benefit of the doubt (and it's not like Reverb would have given me much of a choice as a seller) even though the location and type of ding didn't make any sense.
Luckily it was a wood cabinet with a very thin finish, it was easy and fast to steam it out and refinish it.
A few months later though I found in his feedback that another person seller got his cabinet returned for the same reason...
And that's the thing: even if your guitar arrives as described a dishonest buyer can simply add a ding/scratch/crack, claim it wasn't as described, and force you to take it back at yours loss.
Reverb's protection is borderline price gouging: they charge 2x the cost of the already expensive carrier's insurance.
They never gave me a straight answer as to whether they cover more than the carriers do (who can easily deny a claim). For double the price it seems that all you get is Reverb handling claims for you, which can actually be worth it given how painful and long the process is with carriers.
They do have a nice shipping discount on UPS though, but if you get their protection it's still end up being pricier than buying a label from a UPS Center (not UPS Store as most of them also charge 2-4x the price of insurance as a way to make a profit).
I recently got my own music instrument insurance which covers shipping damage/loss too.
That way I can take advantage of Reverb's shipping discount for sales below $1.5k, and anything above that gets shipped straight from UPS/FedEx.
