Posted By Dan D DuBal
I do know that the Orion Expanse and Skywatcher Ultra Wide eyepieces are indeed "siblings" (same manufacture). The LER eyepieces do have a little more eye relief (20mm for all), but the 13-to-17mm provided by the various Expanse/Ultra Wide units is likely sufficient for most applications (i.e. viewing without glasses).
I haven't been lucky enough to try *either* design (same goes for the ED-2 line), but I would expect them all to provide nice, comfortable views with reasonably good fidelity. Yes, f/5 will challenge most any eyepiece off axis, but these particular lines should still do a good job axially (central 60%-75% of their fields).
I'll likely try one or two from the Expanse and ED-2 lines, myself. If I like them, I'll definitely come back to the forums and say so.
I'm sure several Astromarters will chime in and share their own experiences and impressions with the ED-2s, Expanses/Ultra Wides, and the LERs. In fact, you might end up with a LOT more feedback than you ever expected! :-) Just enjoy it.
Best wishes and luck.