If you are interested in this issue, there is a website for the idea here.
I believe that it would be beneficial for the region to develop the overpass. You only need to go through that area to see how important it is for traffic for Greater Victoria.
I know there are people that say if you built it, the problems will simply shift to Tillicum and Hwy #1, I disagree. A large amount of the traffic is to and from McKenzie to Hwy #1 which is why there are long storage lanes for left turns onto McKenzie.
The traffic delays at Tillicum and the highway would not become much different than they are now, though people would gain time getting there. People headed to the Tillicum Gorge Neighbourhood would see significant improvements in time, it also makes a big difference for commercial traffic headed to Esquimalt as they have to use Tillicum and not Admirals. For traffic going to and from McKenzie it would make a huge difference, though ideally there should be some changes to Burnside and McKenzie.
Long term I would like to see McKenzie from the Pat Bay highway to Highway #1 be made into a freeway, it makes the most sense to allow for the traffic in the region to move most effectively, especially all the commercial traffic.
There is another interchange/overpass I would like to see make a priority - the one at the Pat Bay Highway and McTavish. As our airport increases in traffic and traffic continues to increase on the highway, it would be beneficial to remove this traffic delay. Long term I would like to see the Pat Bay be a full freeway from the ferry to town.
Ultimately the traffic problems in Greater Victoria are not dramatic and we can live with the Colwood Crawl. When one looks over at the lower mainland, then one sees what traffic problems really look like.