Hi Matt,
I had virtually the same injury from skiing many moons ago, but I didn't realise i'd totally ruptured the ACL at the time; I thought it was only a partial tear. I found out otherwise when my knee gave out one day as a result of cartilage damage (bucket tear) and an op for that revealed the ruptured ACL!! Anyway, I wasn't a runner at the time, and because of the time lapse between the actual accident, and the cartilage op, I didn't bother getting reconstructive surgery. I did get problems with my knee last year when training for a marathon, specifically in my medial ligament, but this came on after running downhill, and I don't think it was directly correlated to my previous injury, but it impossible to say.
I'd always err on the side of caution when it comes to surgery; if you are doing okay without it, why put yourself through it? It will take a while to recover, and you also have to think of missed time from work, commuting issues etc etc. I think with a good strengthening program, and any rehab stretches or work your physio has given you, you should be okay. I did lots of quad work when I had my accident, and that saw me though, albeit I wasn't sporty then (other than skiing), so I wasn't gearing towards recovering so I could run again.
Have you taken advice from your consultant at all in terms of whether they think surgery is worth it at this stage? I know two people with the same injuries, and both had ops. One is back playing football (girl), and the other isn't (boy) as his knee is just fecked for it! Sorry if this isn't exactly stellar advice, but in my experience you can do okay with the ruptured ACL and damaged medial ligament. Good luck!