Just to chime in.
You should be able to OC to 3.9Ghz with the Stock cooler with the 1700 without any problem; Its the first time that i actually see a good stock cooler delivered 
And you can use a cheaper B350 mainboard too, since both chipsets support overclocking.
Generally you will be very happy with the Ryzen, but you should know that it may take 1 or 2 months until the stability is ironed out through BIOS updates and updates in the windows scheduler (which is currently killing 8-core performance a bit with SMT on).
Cheers,