You're welcome to come and listen to my setup, but I don't have the Tiny Dancers but their (slightly) bigger brother. I don't know who is modding the BE-718, but I have rewired my Mini Dancers.
What I can tell you is that cans and speakers will sound very different from each other. Tonal presentation apart, the coupling of the driver to your ear is unmatchable by speakers, so in a sense headphones will win that war. On the other hand, speakers move much more air and the presentation can be much more impactful and tactile than 'phones.
I had the BE-718 (with associated stands) for about two months before the Minis became available. Those speakers sound a bit different. I was driving them through a chipamp, and my impression is that the BE-718 is tonally a touch softer and gentler than the Mini Dancers. The amount of detail is staggering without being overwhelming (which the Dynaudios, my other option, tended to do). They are fairly revealing of the source and the chain, and will reveal differences, sometimes to your chagrin as it will not end with just buying speakers.
The bass is the special part of the speaker, it generates copious amounts of low end detail and impact, though it reaches only 42Hz it sounds like a lot more.
As for power, I was using a 60 watt/ch chipamp. Apart from the occasional headbanging session, the amp was enough to drive those speakers without issue, and I had tricked out the amp so it performed much better than its modest origins would seem to indicate. However the BE-718 was fairly honest about the fact that it needed a wee bit more transparency, and helped me tune the amp to the point where it was satisfactory. I would say 50 good watts are enough for that speaker in a medium to small room.
And finally, placement, I had the speakers about 7 feet apart, toed directly into the listening position. I was right up against the back wall with my couch, and the speakers were about 3.5-4 feet from the front wall, one speaker was in the middle of the room and the other was about 4 feet from the side wall. The bass and detail were adequately balanced this way.