About a year ago I tried converting some 1411kbps WAVs to ~256 kbps VBR mp3s. A/B against the original WAVs, I felt the two were "virtually" indistinguishable. Once a DSP was added to the mp3s, the mp3s sounded superior to the original WAVs. Superior, but signal fidelity was not preserved (it can't be preserved if it's improved). My recommendation to retain WAV format, if possible, is on the theory that the original signal record is best kept intact until you actively change it (as with a DSP). Obviously there are practical considerations that intervene, but plenty of newcomers to digitizing may not understand the concepts beyond digital=mp3. I was one of them; the first time around I ripped my entire collection to WMA 160s.
IMO, if you're satisfied with mp3s, sign up for (legal) Napster. I did, and it has opened my eyes. For $10/month I doubled my library. Let's go back to that 500-cd collection costing $7500. You're going to take the time and effort to rip all those to mp3, when you could just download them over 3 or 4 nights? Fully tagged and in proper directory structure? Oh, and the cost? At $10/month, it would take you 62.5 years to pay off the 500 cds. At my age, I like my odds with Napster.
IMO again, the difference between WAV and mp3 is paltry compared to the difference between a good and bad mix. Clipping, flat staging--nothing can save a lousy mix. Beyond that, going from analog to WAV throws out much more signal than going from WAV to mp3. Therefore anyone converting CDs to mp3s can take heart. But if you have the choice, retain the signal intact as far along the path to the speaker as you can.
12,000 albums? You spent serious money on them, unless they're punch-outs. Today that 1800 gigs costs less than a grand to double your capacity, and you spent a LOT more than a grand on your music. As for the 4 1/2 years you've been working on it, join the darn club. We're all going to have to keep re-digitizng anyway, as standards (hopefully) improve.