I think the need for toe-in differs from speaker to speaker, and then from room to room. And it also depends on the listening position (distance from speakers). I don't think the need for toe in or the lack of it depends on the type of speaker.
In my very limited experience with trying to get my setup right, I found that all those rules of room placement can only be used as a starting point. None of those room placement techniques worked for me out of the box, so to speak.
I started off trying the rule of thirds and abandoned it halfway as the way my room and the furniture I couldn't get rid of were, I couldn't place the speakers or my listening position right.
The cardas calculations didn't result in a satisfactory positioning, but a bit of variation from the results of the formula sounded much better to me.
Finally I tried the real traps technique, and though sticking to the exact percentage didn't sound good, a slight variation of it worked.
As far as toeing-in in my setup is concerned, full on toeing-in results in the music sound too aggressive. Zero toeing-in made some of the background instrumentation make the speakers too "visible" and the center image too weak. The center image is better with full on toe in, but I compromised with about 40% less toe in than 100%. This means that just like in your case, the long part of the isoceles triangle closes about 2 feet behind my head.
In your current setup, going by just the distances, I think the speakers are a bit too far apart considering your listening position. Maybe bringing them a bit closer, after considering the other non-hifi factors, might sound better.
You might also try toeing in just a bit, trying to arrive at a compromise between soundstage width, center image definition and soundstage depth.
IMHO, the steps in room placement should be as follows:
1) Get the relationship between the speakers and the walls behind them and to their sides right (using a listening position equal to, or about 10 to 20% more than the distance between the speakers).
2) Further tweak the distance between speakers in relation to the temporary listening position.
3) Get the distance between your listening position and the speakers right by changing the listening position.
4) Get the toe-in right (or finally decide toe-in is not needed).
5) Revisit step 2.
6) Fix reflections on the floor and the side walls to the extent practicable. Usually the floor is easily fixed. The side walls are another story. I'm not even thinking about the ceiling or the wall behind the speakers.
About the distance between you and the wall behind you, that will be a result of all this. I don't think we can really account for that also considering we are more concerned with (clearing) the furniture and other things in front of us.
All this is IMHO, what I've learned from a lot of reading and a bit of practice in my case.
Sorry for a really long post (as usual). I really should try and be more succinct
