So I'm looking at the first Bestiary, Appendix 2, titled "Monster Advancement", pages 294 - 296. For those of you who don't have the book handy, the information is on the following page of the PRD: Monster Advancement (although for some reason, the "Reducing Hit Dice" sidebar from page 296 isn't there).
I'm wondering: by what criteria do you decide whether to apply the "young" template to a monster, or whether to reduce its racial hit dice (assuming that the base monster has more than one hit die)?
Is it simply that it's easier to use the template? And if that's the case, then does reducing the hit dice give better results? Or are there entirely different reasons why you would want to reduce hit dice rather than use the Young template?
Obviously, all the same questions apply to adding hit dice vs. using the Giant Creature template.
It really is easy to use the templates to adjust your monsters and does a reasonable job, particularly for adjusting the power down. I'd adjust hit dice if I really felt that I needed a change that the template doesn't quite do... generally going above the power of the enhancing templates.
you can only apply a template once so if you need to lower the CR more than 1 then you have to lower the HD
Thank you for the replies!