Templates on Low-CR Creatures

[AdamMeyers]

Are there any rules about how templates work on creatures with a CR of less than 1?

Adding a +1 CR template to a creature who's CR is 1 or more is simple, but what does it do to creatures who's natural CR is 1/2? or 1/4th? or all the way down at 1/8th? Do they round up or down, or should they move one 'step' higher instead of a full +1 CR?

And even if the rules would be to round them up to 1, what 'should' it be instead, given that a celestial bat is much weaker than a celestial dog, whatever the rules say?

[Chess Pwn]

+1 should just bump them up 1 step. 1/8th -> 1/4 -> 1/2 -> 1

[John Murdock]

+1 to CR to a creature with a lower CR than 1 make them go up to the next close CR that is below 1 (or make them go to CR 1 if its the closest one)

Example: you give a human warrior CR 1/3 a template that boost its CR by 1 he is now CR 1/2, if he was a fighter instead his CR is 1/2 and with the template he is now CR 1

[Serum]

It's assumed to bring the creature's CR up by one step.

However, if you spend some time looking at the simple templates, you'll quickly find out that they are unbalanced based on how low/high the original CR is. The templates that change based on the the creature's original CR are better.

For example adding 4 attributes to each ability score(as per the Advanced simple template) makes a creature originally at CR 1 much more difficult than creature at CR 2. This is because creatures at low CRs not only have lower starting score (and therefore the modifier is a larger percentage of its scores), but also relies more on those scores than they do on additional abilities.