All depends on what you need, if the benefit in power and upgrades is worth it productivity wise or personally then yes. I just picked up a 2017 Touch Bar and have no problem with what I use it for and the benefit of picking it up like new open box for a great price outweighed the additions to the 2018. The keyboard doesn't bother me and True Tone doesn't make a big difference in my opinion.
I think 1700 is priced way too high for a used 2017. For reference I have seen several sales for brand new 2017 Touch Bar models for around 1400. I think you will likely see between 1200-1400 depending on condition, accessories, etc (if you're talking USD)
Its a 512Gb one, is why its priced so high. I have the keyboard replacement program for piece of mind and with that also comes a new battery. I'll probably just save the money and hang on to what I have. The most extensive thing I do is I dabble in photoshop anyway.