The Ultra's are a better speaker than the Infinity R162, but we are talking $1000/pr (or $800/pr for B-stock) for the Ultras vs $162/pr for the R162 (when on sale). From a value standpoint, the R162 have an easy lead over the Ultras because they are still very good speakers. Let's just say there is a huge gap between your Onkyo's and the R162's and a smaller gap between the R162's and the SVS Ultras. However those relations are not reflected in their prices.
The problem with SVS is "it sucks to be selling a speaker at list price right now because there are so many good values for discounted speakers"!
If you are considering spending the money for the Ultras, I would say don't! I cannot recommend them at this point because of what Canton has done with trickle-down to certain models of their Chrono SL Series!
I would put this particular model of Bookshelf and Center up as better than the SVS Ultra series:
Bookshelf for $520/pr.
www.accessories4less.com
Center for $400:
www.accessories4less.com
So for $920, you are getting the mains plus center for about what the Ultra mains alone would cost and they are better speakers. However, Accessories4Less is reporting low inventory, so they could run out, but they also are likely to get the next year of stock in soon (it appears that A4L orders a couple of shipping containers of Canton speakers every year).
But let's recap:
1) Infinity R162 Mains plus RC263 for
$324
All the speakers you need for your home theater, under one roof. Floorstanding speakers, bookshelf speakers, in-wall, outdoor speakers, subwoofers, & more.
www.harmanaudio.com
2) Canton Chrono SL-536.2 mains plus SL-556.2 for
$940
3) SVS Ultras for
$1700 (or, if it fits, I would go for three bookshelf speakers and B-stock for your RCL, which would reduce the price to
$1200)
4) Because you said this system is for HT only, I've got to mention the JBL Studio 5 Series which is also heavily discounted to
$440 for the 530 mains and 520 center:
www.harmanaudio.com
These are a compression horn design that I find very engaging for HT (and Rock) because of an effect that seems to make sounds more immediate - it is a little more exciting when you are on the edge of your chair watching an action movie.
Since this is for HT only, I would save some money and go for the Infinity or the JBL Studio 5's! Either of these do a very fine job with voices and sound effects! It is when you are trying to get the sound of a trombone or a symphonic chime
just right that the Ultra/Canton will show up as better speakers.
I find the Infinity has a slight edge for speech intelligibility and the JBL for excitement, but either will blow away your Onkyo speakers in every aspect of sound quality!
Please don't misinterpret my comment about the Infinity having slightly better speech intelligibility! The JBL are very good speakers and are not at all poor producers of speech! We are talking fine differences!