Compare two counters?

What is the best way to compare the value of two counters? With the ElkRP, I can only compare a counter to a custom value, not to another counter.
There is not a two counter comparison on the M1 Rules programming. What is your application? Maybe we can have some other ideas.
I'm investigating creating an HVAC zone controller using the Elk rules. These zone controllers just seem to be event driven state machines. I was using counters to create virtual thermostats (hence negating the need to buy expensive communicating thermostats). There were some events where I needed to compare two different temperature readings. Every interval I would read the thermostat value into the counter and use the counter value for comparisons. I was trying to reduce the frequency of thermostat readings (assuming this is an expensive operation). The counters essentially cached the temperature reading and allowed me to incremeant and decremeant before comparisons. I may have to rethink this approach.