The biggest difference is horn vs dome tweeters
Bob - I recently went through a very similar decision, which led me to the BIC Venturi's. However, based on what you've indicated, the Acoustech's might work better for you.
First of all, the biggest difference between the two is the tweeter system. The Venturi's use a dome tweeter and the Acoustechs use a horn system. This create's a sound difference, which becomes a matter of personal taste. If you can't listen to the BIC speakers (I know I couldn't where I live very easily), try to get out and listen to Klipsch speakers with a horn tweeter, compared to another speaker with dome tweeters.
From what I have heard, the horn tweeters work particularly well when the application is movies vs. music, so that might lead you more towards the Acoustechs. The downside to horns is that some feel they sound too harsh or "bright", but as I said, that is a matter of personal taste.
Some other considerations: I like the looks of the Acoustechs (with the high gloss lacquer tops and bottoms), although the Venturi's look nice too (just not as stylish). Also, the Acoustechs are more efficient than the Venturi's, which means they produce more sound with less power. Therefore, if your receiver has lower power, you may get better sound from the Acoustechs.
For me, I have (or I should say will have) a higher-powered receiver, and I tend to listen to more music than movies. I also prefer the sound of the dome tweeter with the kind of music I listen to. So I went with the Venturi's.
Anyway, those are just some things to consider. Both systems are a great value, and I'm sure you will happy either way. Lots of luck.