Jeff, i have been asked these questions many times. i agree with many here, there are many perspectives. i am one who has always attempted to try to have state-of-the-art players for both digital and vinyl. recently; i have also pursued state-of-the-art reel to reel. to me one of the fun parts of this hobby is comparing formats.
when i have visitors over we first listen to digital then at some point i put on an Lp of the same music we just heard in digital; i love to watch the look on their faces and the jaws dropping.....then a big smile and a shaking of the heads.
what does it take to get this difference?
the big difference between vinyl and digital is that with vinyl everything matters alot. there is so much more information in those grooves that at almost any level of vinyl changing the right thing will take you further.....and you will likey clearly hear the change. this makes moving up more fun.
in the past i have said that the right tt, arm, cartridge, and phono stage purchased for $10k-$12k new or around $7k used would potentially take you to a performance level where most listeners would easily prefer Lps to digital. as you step that up there would be more 'wow' factor at higher levels of investment. as you travel up the foodchain you have much lower levels of noise; better speed accuracy, and higher levels of refinement.
recently 2 things have changed my perspective on this equation. first; i have a new digtial player, the Playback Designs MPS-5, that likely raises the stakes for vinyl to better digital by another level. for a vinyl rig to exceed this might take another level, maybe $3k to $5k more. second; there has been a bit of discovery what the performance of some vintage direct-drive and rim-drive tt's when combined with top level arms and custom plinths can do. this lowers the investment level of very high level vinyl performance.
so digital is better, but very good vinyl performance has become less expensive to aquire if one goes after these vintage tts.
regarding how much Lps vary; i have 7,000 or 8,000 lps; 90% sound good to great. the others are varible. most of those 'others' were purchased for less than $1 each.
i would add in fairness that many Lps have tics and pops, and the sensitivity to those issues varies from person to person. some people enjoy cleaning records and the little tweaky things one does to get the best results. if one likes the sterile and clean aspect of digital then maybe vinyl is not for you.
a month ago a friend, who owns a record label, used my tt to record some direct-to-disc Lps to make an K2HD recording. he had purchased the rights to these Lps and no master tape exists. he brought 3 pro audio guys and 2 hi-rez recorders; a Pacific Microsonics II (recording at 176/24) and a DXD (recording at 386/32). during this session; we did many test recordings back and forth between the tt and the two state-of-the-art digital recorders.
you would think that these ultimate digital recorders could make a digital recording indistinguishable from the original Lp. if you thought that you would be very wrong.
as good as the digital sounded; the Lp still smoked the hard drive based recordings. digital (at whatever resolution) simply cannot get the whole picture.
the real question is.....is it worth the trouble?
you bet.