I don't have a huge collection however I have experience here. I had a house fire in 2014, mainly smoke damage but actual fire damage and heavy smoke affected a room I had quite a bit of train stuff in, N, HO, and O scale. My homeowners policy is through Nationwide. I had two adjusters, one for the house, the other for the contents, all the same policy. The contents had a maximum, I didn't reach it though as many items were able to be cleaned. The trains that could be salvaged were sent to a professional cleaner that specializes in high end electronics all handled through Nationwide. The experience was a smooth as possible for such a life disruption.
To the trains which were claimed. The adjuster had a software tool where she entered all the general items, beeding, pots, pans, TV's etc. For the hobby items (which also included RC cars) she documented them with generic descriptions and photos. I then had to provide detailed information on replacement costs. For items no longer made, I gave here results of ebay listings, she generally based the reimbursement on the highest one. For items which could be replaced (even if new was a major upgrade such as PS1 versus PS3) I would get the new value. Now, the catch is you get a check for this, but only at 80% of replacement cost. I got the remainder 20% when I provided proof of replacement purchase. In some instances with the RC stuff, I couldn't do exact replacements and the remainder 20% reimbursement was still honored.
I kept it all honest and my adjuster never questioned anything. I had a year from the original claim date to come back and claim items which may have been forgotten.
This was my standard homeowners policy covered under the contents section. I had no issues being reimbursed for track, rail cars, locos, or any of it. Keep in mind policies are all different and you need to be aware of exclusions. Like mine I believe excludes jewelry and firearms.
Your mileage may vary.