I probably wasn't clear enough in my goals - a typical programmed scenario would be each of the 5 I/Os on the '85 would be outputs connected to LEDs (with approprate resistor), however I assumed when the device is being programmed, having the LED still connected to the same pins as being used for the ISCP would cause problems, especially if the programmer could not provide the current to drive the LED too.
What I wasn't sure of was if all the '85 outputs were connected to transistors to switch the LED current, whether that would still be consided 'risky' for the programmer?
In the name of experimentation I tried it out - with LEDs direct, definite fail with programmer failing to detect the device. But with 85 driving LEDs trough uln2803 gates, I was able to program successfully.
I fully appreciate just because it appears to work doesn't mean it's not actually doing untold or undetected damage, which is what prompted the question in the first place.
But as I understand it with the 2803, I'm only ever connecting outputs to inputs (run time) and outputs & inputs to inputs (program time) but never outputs to outputs so it should be safe.