Had a question I hope somebody could give me insight on.

I got a ATtiny85 project finished and working great with the full library and hardware PWM sending NEC at 8mhz.
It's powered by 3.3V, so max I can run is 8-10mhz. This is for a CNC probe so reliability and battery life are priority.

I do need more pins though, so I upgraded to the ATtiny814/816 only to find problems converting the code.

It appears the library does not support hardware PWM with the series 1/2 ATtiny, although the docs show the default timer and hardware pins used for these chips (PA3)?

The docs also state there is problems running software PWM at 8mhz with the AVR. (This is why I choose hardware PWM at 8mhz)
Finally, it also states TinySender runs at 1mhz, but it's not clear if it can run faster?

So, I'm stuck trying to figure out what path I should take for best reliability within my constraints.

My options seem to be the following:

1. Upgrade the ATtiny85 to ATtiny84, keep the code the same, running full library with hardware PWM at 8mhz or less. (I'm trying to avoid this as space is very limited, and would like to use the same newer chip for both sender and receiver)

2. Upgrade to Attiny814/816, running the full library but use software PWM at 10mhz. (Docs not recommended at 8mhz). Not ideal because of both accuracy of the signal and higher power requirements at 10mhz. It's also not clear if the step up from 8mhz to 10mhz will avoid the accuracy issues with the AVR chips? Does that issue not apply to new AVR chips with different timer architecture, can I use hardware PWM?

3. Upgrade to ATtiny814/816 and switch to TinySender at 1mhz or higher if possible? I would like to run it faster as it's a critical application.

Or am I missing something that's a better option?

Also curious is it okay to run the sender and the receiver at different clock frequencies? (with either the full library or TinySender/Receiver)

Thanks for any ideas or input!