Based on Trillians Unification Features Summary and Comparison chart the following features are available to us when we use TrillianPro to IM with someone using AIM

Versions Used:
TrillianPro version 3.1
Homepage ~ http://www.ceruleanstudios.com/
Download: http://www.ceruleanstudios.com/downloads/

AIM® Triton v1.0.4
Homepage ~ http://www.aim.com
Download ~ http://www.aim.com/get_aim/win/latest_win.adp

AIM Triton and TrillianPro v3.1
I have one AIM ID running on AIM Triton (beeageek) and another AIM ID (beesitoy) running under Trillian Pro

typing notification works a treat both ways (and reliably so :)
TrillianPro detects typing on AIM Triton	AIM Triton detects typing from Trillian Pro

no issues with file transfer...
TrillianPro can easily receive files from AIM Triton	AIM Triton has no problems receiving files from Trillian Pro

I struggled with getting my AIM Buddy Icon (display picture) to show in Trillian Pro, it wasn't an issue with Trillian though, it was caused by my being an AIM newbie, I had to enable this via my AIM preferences under..
Edit > Settings > Expressions, then under Buddy Expressions select All Buddy Icons

I can't webcam either way. ..
Trillian gets stuck on...	AIM Triton...
	thankfully generates an error message not exactly helpful I know but something is better than nothing

I switched to AIM v5.9.3861 to see if this would resolve my webcam issues... no joy.
I headed to my Mac, fired up AIM for Mac v4.7... not an option. I can send the invite to AIM but nothing pops up regarding the requrest... my black screen remains :( I then headed to iChat v3.1.4, another dead duck. Either I have real issues with AIM (both versions) and ICQ or there is a great deal of confusion on Trillians side regarding which ID belongs to which IM provider...