Hey there,
I have been using the Polystyrene hives for more than three years, and I will say they are amazing.
They keep the gals warm in the winter, and cool in the summer.
The hives have wintered over each year, and start building like crazy in the early spring.
I would really recommend them, I have also wooden hives, and found them to be fine, though the shear numbers of bees that overwinter in the Poly, seem to be a whole lot more.
No Ant problems, nor mice, or any other problems.
I had a bear last year, tore the hive up, but was able to put it back together with Gorilla Glue, and it is still holding strong today.
I think your mentor has moved you in a good direction, ask 10 Beekeepers what they they, and you will be sure to get at least a dozen different answers,
Just the nature of the beast.
Good Luck, and DO IT, if not both, maybe one of each, that way you can have your own laboratory and view the difference between them both.
Have a GREAT BEE SEASON!!
IT is a whole lot of fun!!!
Cheers,
JT