If you can inspect the machine. Ask them to do the following:
Load new media. (Make sure it loads properly using the auto feature.)
Provide your own test print file and have them print it.
Make sure the take up reel works properly.
Check the carriage area for cleanliness.
Ask them if there are any known issues.
We love the HP series latex roll-to-roll printers. The quality of the prints are great. The speed of the prints are in line with competitors, and it's super easy to profile new media. We will purchase new latex printers in the future as they cost very little compared to solvent printers, but we will wait until the new model is released. We may even give HP the first run for dye sub printers based on how well we have worked with the HP latex. If their flatbed printer was not slow for the number of sheets per hour then we may only have HP printers in our production, but right now it's far behind the Vutek and Durst which is understandable based on the price and it's the first series for the flatbed. HP makes a great product and they stand behind it every time I've had an issue to this point. Most issues I've read about HP latex are user errors. That is not to say that some lemons have not got through their production lines, nothing is perfect.
We recently purchased another used latex 365 last month. The printer arrived not as described by any means. But this is where HP does a great job. It only cost us $50 to speak with a tech support to troubleshoot. This is done to ensure you need someone onsite with parts. Then we paid $1500 and HP sent us a 3rd party tech support person and he was wonderful. HP replaces/fixes everything that is wrong with the printer when the tech support person arrives. They overnight the parts and it does not matter if it takes 1 day or a week of the tech being onsite. It's only the $1500 and it covers ALL parts! Our tech person went over it and made sure by the time he left there was no issues with the printer.
I purchased the printer cheap and thought I was getting an amazing deal! But even after I paid $1550 total to fix it the price was still below $6250 with shipping. I doubt I could buy a used printer for that price in the condition this printer is in now, so it's not so bad! The printer now has new motors for the take up, motor for the reverse wind function, scan axis reader, etc... let's just say we are very happy with HP and the way they take care of the users after about 9 boxes arrived with parts and it was fixed in 2 days.
Good luck and I highly recommend the HP 365+ series!