I've been using my Binotron27 for a couple of weeks now, and really love it on my 12" Dob.
Ease of use:
It is so easy to use, that I literally put it in my focuser, and adjust to focus, and then observe ^_^ With the power swtich, I can easily change from 1.3X to 2X and 3X. Currently, I am using a pair of 40 mm plossl (49X, 76X, 114X), and 20 mm 68 degree (99X, 152X, 228X) and considering to get a pair of ES82 11 mm for really high power. The only thing issue I have is that, for 114X and 99X using 40 mm and 20mm eyepieces, I can not focus and need to pull out the Binotron a little bit to reach focus, but not difficult.
I most use the binotron27 for planets and bright DSOs. Saturn and Jupiter are great, and I can see some small details on them. Actually my best view of Jupiter with clearly a moon shadow transit is from binotron ^_^ I also observed M57, M15 etc. Very beautiful, especially for M15 globular cluster, I feel can see so many stars, and lanes.
I also used it to look at the moon, and somehow, I can not merge the two views (for Saturn and Jupiter, I have no problems to merge the views from the two eyepieces). Not sure if this is just due to my inexperience. I found it is much easier to view in just one eyepiece. Also, the binotron27 is heavy, that I have to remove my finderscope and fasten the knob to lock the altitude movement for my tube, I think I will need to buy some counter-weights soon.
Anyway, I am really glad of having this binoviewer, and definitely love it! I will continue to use it for more observations, but at this point, I still love mono-viewing for fainter objects, I don't think it will completely replace my other eyepieces like others do ^_^