I have to admit I haven't heard of Reman.

Despite their name, they do not actually re-manufacture transmissions. They are just middle-men. From their 'About us' page:

We are able to offer the most extensive variety of remanufactured transmissions and transfer cases by partnering with the nation’s leading transmission remanufactures.

That being said, the product warranty sounds pretty good: 60 Months/Unlimited Miles

They claim the transmissions are well tested

• During transmission remanufacturing process, all worn parts are re-machined or replaced with new OEM parts as opposed to just replacing the ones that don’t work.
• To eliminate the possibility of front seal leaks, vibration, and premature bushing wear, all torque converters are tested for leaks, lock-up, concentricity, and balance.
• Every fully remanufactured valve body, with complete system correction and recalibration kit, is tested independently.
• All wear-prone valves are restored to stringent specifications and vacuum tested to confirm proper function.
• Each remanufactured transmission is hot, cold, load, and simulated road tested using our proprietary CARS (Computer-Aided Road Simulation) dynamometer program.

They claim to have been in business for 30 years. I guess it all comes down to how the company is to deal with if things go wrong.

But, ultimately, none of this matters ....

Unless you've installed transmissions before, you should be going to a dedicated transmission shop to have one installed.

The warranty is contingent on correct installation of course. If you put the transmission in yourself, miss a few steps, and bugger up the transmission, you are now on the hook. You could be buying a whole new unit yourself, and then having to redo the installation which is no picnic without a lift.

The warranty included with the transmission covers that transmission only. A large portion of the price you will pay is for the labour , which is not covered by the transmission supplier. This is covered by the shop's policies. Now, the shop doesn't want to have redo their work for free either, because they would go out of business. That means that they choose their own suppliers that THEY trust. And they probably know better than you. If you bring your own transmission to them, they might install it for you, but will provide no guarantees (you're still on the hook)

If you let the shop supply the transmission, and something goes wrong (whether it's a defect, or mistake in the isntall), you just take it back. You don't have to spend hours on the phone arguing with the supplier. If the transmission is bad, the shop eats the labour cost. If they're smart, they are going to use a large reputable supplier. (maybe it's Reman after all, who knows)

So if and when the time comes, go down to your local tranny shop and have a short meeting with them. Ask questions, and go over all the details with them . What is the warranty, what is covered, etc...

Never heard of that company. The fact that they do not seem to provide a physical address and their only contact is via toll-free phone number or an email form on the web site is a bit of a red flag. I'd want more specifics about a company before buying an expensive item from them.

Internet reviews can be spotty since they're so easy to fake but there seem to be quite a few negatives out there which is a concern. (In general you want to focus on negative reviews since so many companies post phony positives. In my area there were tons of favorable reviews online for a restaurant that had not even opened yet!) For example:

https://www.trustpilot.com/review/reman-transmission.com

https://ratingfacts.com/reviews/reman-transmission.com

As long as you change the lube periodically and don't beat the thing to death it's unlikely you'll have any problems with a Honda manual transmission. (Older Honda automatic transmissions are a different story.)