There is a very simple endorsement for the fine merits of the LV's in that they essentially continue to exist to this present day largely unchanged reincarnated under the name NLVs. The optical design/components are identical and Vixen has simply changed the eye cup shroud to a plastic twist-up in the NLV's.
For what it is worth the apparent logic for this change was to accommodate a marketing perception of continued refinement in the development of their eyepieces and to appease apparent complaints (perhaps from a vocal minority - I don't know) about the original rubber fold-down eyecups.
FWIW - I have tried both the LVs and NLVs and while I found their image to be identical I always found the LVs to be more comfortable to use. Having said that some of my favourite current eyepieces are Pentax XWs which are all twist tops
Today the LVs 2nd hand represent superlative value for money but if you are hell bent on getting them and can't find them then the NLVs are always readily available and all things considered remarkably cheap even brand new.
I am continuosly amazed at the price for some EPs which carry a certain well known brand name, made of standard ED glass and these days are largely made in Taiwan (there still remain a few exceptions).
In comparison the Vixen LVs/NLVs/LVWs to this present day (as do Pentax EPs) still maintain the original mantra of being genuine Japanese optics with all the QC features and utilise Lanthanum glass.