From past and present NSX insurance experience with both paying insurance and making a claim... I believe only evaluating yearly cost can be a BIG/COSTLY mistake with the NSX.
I'd focus less on yearly cost and more on the what if's. Often times it's better to pay more on the front end than on the back end. Here is what I mean.
I had a fender bender in my 91 NSX back in 2004. Total cost was around 20k for repairs. I paid 35k for the car in 2000 (low miles/lots of mods by teh right shop). I was hit right where it got one headlight, the hood, the fender, the front and lower bumper cover, the spoiler and slight damage to a quater panel... Looking at images the damage was very minimal. I paid my $1000 premium (had it high for low yearly payments which did pay off some as it saved enough in 2 years to make up for the one claim I had to make
) and the work began... only I ended up paying about 12k out of pocket and the insurnace company did 8k of the damages so the NSX wouldn't be totaled from cosmetic damage only b/c book on it was 19k and at the time and I still owed more than book. They wanted to total it and hand me a check for 19k so I'd be buying an NSX that didn't exist, plus I'd be out buying anotehr NSX. Call me nuts but I wasn't going to let a little comsetic damage remove such a great NSX from the road... and I'd rather pay more and get my car back than be paying and not have one plus have to be paying to get another NSX. This paid off eventually b/c I documented all the damage with really good photos... kept all receipts and promotional info about the Ferrari body shop that worked on the X for me... I also had the entire car painted to match and could show that no expense was spared to get the car right SO I was able to sell the car for a premuim last year when I went to sell it verses doing it all wrong and only being able to get 19k for it.
Here is what I am currently going through... I just purchased a 98 NSX-T with SOS CF WIDE BODY KIT/COMPTECH SUPERCHARGER and many many more mods... book on it is 43k. Loan is 35k. State farm quoted me what seems to be a great deal at first... 1100 a year with it as a daily driver and less if i used it as a toy... I find many NSXers I've talked to recently stop there... being that I lived through the fender bender in my 91.... and paying 12k out of pocket was a real bite in the rear end... and knowing how much insurance companies undervalue what NSXes do sell for... I'd go a little further.
The deal State Farm offer me seemed like great covereage at a great cost... but knowing what I know now... it's good until you put them on the fence about covering the car in total loss area... after careful scrutiny and multiple opinions from state farm experts over the last few days... they informed me they'd give me NADA book value... which (depending on miles/condition) is like 35k-40k they say (I haven't checked)... so I'd basically be 20k in the hole if I were hit and it was totaled. Ask them what they'd give you for teh car today if it were totaled... you might be surprised!
So be really careful... from talking with NSXers over the past few weeks, with highly modded cars, who paid over book value, at 2 different BIG NSX events here in FL... I think some NSXers might be under insured. I found out last time the hard way and it's no fun. I've put about 20 hours into insurance calls/research over the last few days and keep hitting the same dead ends at all the insurance companies I talk with... even the enthuiast owned companies like Hagerty's... I'd really be looking at what the NSX sells for/what you are paying for your NSX.... what you'd owe if it were gone and they only handed you book value over yearly cost as you'd have to own it for a really long time with low annual premiums to make up the 20k you'd be stuck paying if you bought the nsx for over book value and they only handed you book(as most seem to sell for over book depending on year/miles/condition/mods/rare color combos/etc.) The NSX is in a strange spot right now b/c it is not a collectable yet as far as age/being an antique... so they still see it as depreciating... yet I'd own two and buy them all day long to sell if they sold for what insurnace companies say they sell for.