the only info that i can give you in this regards is purely anecdotal. i've made 4 claims through progressive. the first one was when my bike was attempted to be stolen and the guy dropped it. did over $1300 in damages. second one, my wife's bike fell over while on the lift, damaging the crash bar and front fender, about $1000 in damages. those were several years ago. but then a year ago last october i hit a deer on the way to work. luckily i didn't go down, but had about $3500 in damages to the bike. then in march, i was rear ended while waiting to make a left turn, totaling the bike.
in all instances, i felt like i was treated very fairly, and didn't have to fight for anything. in fact, because i was able to do the labor myself, i actually made out ahead. in the last instance where the bike was totaled, i ended up with a check for the bike for $25,000. paid $33,000 for it back in 2013 and put 40,000 miles on it. i did not have much in the way of aftermarket accessories, so the the $3,000 included covered what i had added.
now, none of these really affected my rate, except in the last case i went from a 2012 and a 2013 to two 2019 roadglide specials. so, yes, my rate did go up because of the different value of the bike. and i do have new bike replacement for the first 2 years as well.
contrast this to a guy i knew in the military. no tickets, no accidents. got into a wreck and had to fight with geico to get his bike fixed, and then afterward, they cancelled him.
i can't say if they are like that everywhere, but that's my experience here. i have no problems recommending progressive.
oh, and there are at least 3 ways to get progressive. the first is direct through their website. the second through hd insurance, and the 3rd is through usaa. (this is in addition to using a local agent of course). i got a quote all 3 ways. surprisingly, going through hd insurance was the cheapest. i've been with them now for 18 years.