I came to this forum in a similar situation, where I was/am researching the Honda P500, and found this forum. I was eager to get one since after this past hunting season. Just I was all ready to get one, when a deal came up on a nice used boat, like I've been looking for, that I couldn't pass up, so I bought it. Now I am taking a little time, to put the moneys back together, since I'm not wanting to finance this purchase.
So, I have had the same question, on what possible changes are coming for the 2018 P500? My first impression of the P500, was that I really like the compact size, and the idea of control of the transmission, and shifting gears, when I want. The only deal breaker for me, was the fact that it doesn't have a bed! That is one of my favorite features of SxS's in general, but it has none.
After researching here and on the internet everywhere, seeing what others have done with custom bed ideas, boxes, toolboxes, baskets, etc, I can see where this is no longer an obstacle for me, and I think I have that part covered. About that time, I was debating between the 2016 leftovers, and the 2017, with the new AT/MT transmission options, I was unsure again. At this point, most 2016 models are gone, and I've had a chance to test drive the 2017, with the AT/MT options, and I think I like the ability of having both.
So here is where I stand now. Do I buy one soon, or at this point, at least wait for the announcement of changes to be made on the 2018 models, before I pull the trigger on my P500. I'm thinking this may be my best option, since my timeline is to have one, before next hunting season in fall. I'd like to give myself a little time to have the accessories and modifications done, before hunting season though.
I'm thinking I may wait for the changes in 2018, to be made public, before I buy. I'm guessing that will be in mid summer, maybe someone can give a better prediction though? I'm starting to think it's going to be minimal changes though. Possibly just color changes as mentioned. At this point, I'm not sure if a factory bed is ever going to be in the works, as it seems, people have so many preferences and like the flexibility of what they want to do with the rear rack.
Good luck with yours!