Like it or not the SWRR is needed. Badly. Any discussion to the contrary is purely academic. Granted, I am biased because I live in cedarwood and work at MRU so obviously I would benefit tremendously. It will cut my morning commute from 15 mins to about 5. Don't get me wrong, I'm not complaining about a 15 minute commute. The issue is that if anything, and I mean ANYTHING happens on Glenmore or 14th st or sometimes even south Crowchild. This quadrant is screwed. In personal terms: that 15 minute commute turns into an hour. All that extra time behind the wheel gives me plenty of time to think about the effect of all that stop and go traffic sitting right over the water supply.
Will the RR encourage sprawl? Yes. The demand is there and with or without the RR it's happening anyway. As things stand, the increase in traffic will be funneled up 14th and Macleod and then onto Glenmore, necessitating massive upgrades to those roadways. Who thinks that's a good idea? The extra sprawl generated will have to be controlled through other means. Not building essential infrastructure is not a viable method of city planning.
How about transit? That would be great. I would love the option to take a bus to work, but I can't. Buses don't run early enough to get me to work on time and even if they did, taking transit would more than quadruple my commute. If the RR was built and as per current planning, MRU becomes a transit hub, the RR would do the same thing for buses that it would do for cars: provide a direct efficient route to the deep SW.
As for what kind of form the SWRR should take, I think the tunnel would be cool. If the city bought the TBM they could use it for this project, then the Centre street subway and then tunnel under the runway. Then, when it's not being used in Calgary, rent it out!

. ...But realistically speaking, I think the only real option is to negotiate with the province to narrow and slow the RR to a Crowchild style road with a simple bridge over the Weaslehead. If that happened, the existing allowance would go much further. Fewer homes would have to be bulldozed and much less invested up front. If or when Tsu Tisna decided they want to develop along the roadway, the City/Provence can re-open negotiations to expand the road to full fledged 100k free flow.