Would 3 Sierras LCR be improvement over 3 340's for HT?

I currently have 340's LCR, with 2 pair of 200's as surround sides and rears, used 100% for HT, i.e., BluRay movies and HDTV. (Sub is SVS PB10, in moderate size room, ~ 2000 cu ft.) I've read so many glowing reports on the Sierras (though most folks seem to be interested in them for music) that I'm wondering if they would improve on the 340's in an HT setting.

Thus my question: would there be any significant improvement for HT by replacing the 340's by 3 Sierras L/C/R? The comments on the Sierras that have mainly caught my eye are the extreme clarity and 'presence' of dialog. The 340's are of course very good in this regard; I'm just wondering if the Sierras are better. Would appreciate the opinion of persons that have made this transition, again with HT in mind.

I made this transition so I will try to help.
"extreme clarity and 'presence' of dialog" absolutely. I think the biggest difference is the off axis seating, I can now sit anywhere and the dialog sounds perfect and is coming from the screen.
Bass...as you have read everyone here loves the bass and in HT I now crossover at 60hz the blend to the sub is truly seemless you don't know where my sub is. The bass detail on the Sierra is fabulous, I always felt some of the detail went away on the 340SE when I crossed below 80hz. I think this is where some of the better clarity comes from.
I ordered the Sierra's thinking if there wasn't a significant difference I was sending them back but I kept them and I also listen to two channel music without the sub so it was a win win.
The only way for you to know is to here them.

Jeff, as thrilled as you were with the 340's when I auditioned them, it is great to hear you are even more thrilled with the Sierra-1's.

When I 1st played them, I had no other speakers setup, including the sub. The bass was the most obvious quality that struck me. I swear sometimes it was like having a sub playing with them. The other things that I started noticing was how smooth, detailed and airy the highs are, yet without harshness at even high volume. Then, of course, the "you are there" mids, and the spooky imaging, letting the speakers disappear.

I am glad that your 340SE's did not pursuade me to replace my 170 classics, and then Dave announced the Sierra-1's. The 340's are very good, but they were not enough for me to make the upgrade. The Sierra's are a different story.........

debo and mag-neato, Thanks for the comments. Seems like I'm really going to have to try the Sierras out. (Wonder how long before there is a Sierra-2 and we go through this again!) Bill