Thanks! So I'll make use of that memory for static information... I have some lookup tables for thermistor measurements that are a perfect match for that kind of data.
One thought if I run out of RAM could be to store the power data in int arrays... Multiply the floats by 100x and then convert to int, transmit to the main module, then reverse on the other side. Saves two bytes per variable for vrms and Irms. The Ws data would suffice with a 10x multiplier. That way I could store 1 minutes's worth of data in only 480 bytes of RAM.
I'll try to think of a way to work around the 64 byte limit. Sounds like it would be a good idea to send multiple small squirts to minimize impacts. With the easy transfer overhead, maybe 5 measurements before the buffer is full and starts blocking. But if I send them with a couple of measurements in between each send, then I can take advantage of the non-blocking implementation of the 1.0 IDE, no?