Thanks, I'll take a look at both of those links. I do recall looking at AltSoftSerial more than a year ago, but might be worth another look.
I know it would be possible to get s.w. serial to work adequately, if you prioritize the interrupts and code in assembler for max efficiency, cause I've done it with PICs, but it may never be efficient coded in C, and without specifically integrating with the h.w. serial ISR. You mainly have to give the s.w. interrupt precedence, even if currently handling the h.w. serial intterupt. The efficiency will be poor, unless they're both inside the same ISR, and sequenced properly. Probably not gonna work with Arduino.