I don't know the Retro unit but I've been using a pair of
TLA-100A's since the early 90's and love them.
It's quiet and warm. Very, very smooth. If there was a complaint it might be that you can't seem to get what I'd call extreme, radical, effect type compression... it's more of the smooth lead vocal type that you don't notice until you turn it off. It doesn't sound good when you push it hard, so I'd say it's kinda subtle, but that's good.
I have them patched permanently in between my mic pre and my computer, so I always use them when recording. I just mess with the gain reduction and don't use any for stuff like cymbals.
Neither have ever broken except for the light bulbs went out and when I phoned the company they sent me new ones for free. Both have the original tubes.
Sorry I can't compare it to a Retro but I just thought I'd tell you my experience.
