Personally I would not put too much effort or money into the Pioneer; it's not a particularly remarkable example of "Quad" technology and considering it's age, you can do better with almost any alternative.
Put another way, if you have a garage, well, now you have the beginnings of a garage HiFi.
The TEAC 2340R, however, if you can put up with the bulk of the machine, is a superior quality open-reel machine that is still sought after by musicians, if only to replay the 4-track tapes made on other 4-track decks.
Open Reel tape decks are not really that popular for various reasons, but the Teac 2340 and 3340 models have qualities that take them beyond the ordinary stereo machines (the 2340 can use 7" reels maximum, the 3340 can use any size ¼ tape reel including the larger 10" reels; both can accept tapes smaller than 7"). Collector value if you don't want it yourself, with the one caution that tape decks are heavy and shipping costs make resale more of a local ("pick up only") proposition.
If you don't want a bulky "project" then pass. Your wife or girlfriend is unlikely to put up with it in a part of the house a guest is likely to see. But if you are a musician the deck is a useful tool that can double as a HiFi device.
