Eyepiece magnifier for E-420/E-520

There seem to be several options. I'm looking for something with good magnification (1.3x would be great, 1.2x okay) that's usable when wearing glasses and practical to leave on the camera all the time (not too protruding). Don't mind having to shift to see the shooting info. at the side, as I already have to as is.

So far, I've heard that the Pentax O-ME53, with some judicious filing, offers better usability for eyeglass-wearers than Olympus' own ME-1? I've also seen mention of a Panasonic offering that (presumably?) should work without any modification. Finally, there are a number of 1.3x options on eBay about which I've not seen much comment.

Suggestions or ideas welcome. Thanks,

--
MFBernstein

'Wilderness is not a luxury but a necessity of the human spirit.' - Ed Abbey