What makes Acros "boring".

By straight I meant true to the negative. Then you see the gradients and grain structure.

More on topic, I did also spot Acros in a pro portrait recently.

I've spent too much time looking at different films in the last year, trying to decide which ones to use.

Well yeah, the Tri-X of the day was grainy and T-Max isn't. Plus of course one is normally more likely to use a faster, grainier film when the light is low.

I agree, most people, me included, would be hard pressed to tell the difference if the print size from format is such as to make grain small or invisible. Getting there can be a different matter as they do require slightly different handling, but the bottom line (print) will be very, very similar.