I use down to a 12mm eyepiece with no problems at all. I do have a pair of Agena SWA 10mm eyepieces but the ER is a bit tight. I think your limited by how dim the image gets, the more aperture the better here, and have read that below 10mm FL it gets harder to merge the images but have no practical experience there. The other way is to use a 2X OCS, or a barlow, instead of the 1.6 OCS or put the 1.6 on the front of the diagonal. A few options, lots of options. I'd try the RKE 15 and 12 mono and decide if you like em enough to go double. Try them in the bino's as a single eyepiece, thats what I did. I prefer changing eyepieces than taking out the bino's to change OCS's.
As for wide field of view every eyepiece above with a field stop greater than whatever the bino's field stop is, will vignette due to the field stop in the bino's. Still can get all of Omega Centauri in the bino's with 15mm 70 degree eyepieces for instance with the 1.6 OCS.
Good choice to start with the WO's
Matt
