Tubes were yanked out of cheap-shit radios too and used because of availability, welcome to industrailist capatilism, if it works in guitar apps though, awesome! I followed a comparo of all the common ts chips and boutique replacements, but the orig jrc4558 sounded best (in a slight breakup-pushing preamp setting) to my ears. Although most all of them achieved similar results, which you could enhance and customise through circuitry. I use to be anti the 4558 phenom prior to getting my jsx, because of how many things I seen the bastards in that sounded like butt. Like an old hissy jap 10band eq that had 12 in it, one for each freq and levels. For overdrive 'feel' and 'tone injection' I prefered the ibanez master series stl super tube. I still love what that thing can add. For more gain/distortion in overdrive its an old old ibanez 'overdrive II' (od-855). Neither had 4558s as far as I can remember. The overdrive II also beat out the original grey dod 250 (which I liked way better then the other 250's that I've tried) for grit and stuff. That was using vintage tube amps however, and the jsx didn't like any of them! So I dug up the only ts pedal I could, a ts10 tubescreamer classic with a jrc4558. Instant magic!
I dont believe they alone make the sound, I just like what it does the most. I cant see the ti version sounding much different, and I wouldn't pay more then a dollar for one. However, the market can get absolutely crazy over this stuff. Capatalism indeed!