Depends how long your commute is really. My commute is similar in that I have around 8 miles through traffic then 12 miles on a cycle path that runs alongside the country road but it's seperate from the road.
I have niterider minewt x2 duals and they're okay but not ideal. Run time isn't great and the flashing mode is way to mental for use in traffic. Plus they have no side visibility. I've been using them and a helmet mounted p7 for the dark bits and a cateye el530 and a teeny flasher for the urban bits. To be honest it's not an ideal set up. The main issues are run time and brightness – the minewts don't have enough run time to use on high for the dark stuff both ways so I need to use them on low and the p7 adds enough light.
I'm getting one of trouts lights which will mean I won't need a helmet light.
I just wish someone would design a light that could be used in proper darkness and had enough side visibilty for urban stuff. I suppose it's a pretty niche market.
My ideal light would have 3ish hour run time on mix of high/low, side visibility, dual flashing and constant modes (like the cateye tl1100 rear light), enough light for fast riding in pitch black – but I'm probably asking for too much.
I reckon with trouts light and one other flasher I may be there.
And I wouldn't use the hemlet mounted p7 for the urban bits.