I'm looking to print with Ninjaflex on my Fisher but wanted to check peoples opinions/experiences printing it without a heated bed.
Am I going to run into endless problems or should it be ok?

You must squeeze it very well on the bed and print the first layer slowly, but it is definitely doable, at least on glass + PVA glue.

We have printed with TPU filament last week, the material is similar as nanjaflex. Hot bed is helpful for the adhesive with first layer. The speed need to be much lower, about 30 mm/sec