I own the Amplitrex tester. It is a terrific, idiot-proof machine that has MANY advantages over vintage testers: it does not have to be calibrated; its display provides step-by-step instructions on what to do; it provides results as real measurements instead of proprietary and arbitrary units; it also provides the standard tube operating parameters to compare with the test results; it provides a "subjective" analysis (good, weak, replace, etc.); it even allows a hook up to a computer to do actual tube tracings (i.e., it will test the tube under varying operating conditions and display the results). But, all of this may be overkill for most users, and it is a pricey machine.
It is hard to say what anyone really NEEDS, particularly if they are new to tubes. Even good information and accurate test results takes experience to utilize properly. Certain tubes can read "weak" and still have many years of very good life left in the particular application (e.g., a lot of small signal tubes, when run gently will sound terrific even when they test bad). A cheap tester that will uncover gross problems (dead tubes, shorted tubes) may be all one really needs. If you intend to buy and sell on line a lot, you may need a better tester.
It is hard to say what anyone really NEEDS, particularly if they are new to tubes. Even good information and accurate test results takes experience to utilize properly. Certain tubes can read "weak" and still have many years of very good life left in the particular application (e.g., a lot of small signal tubes, when run gently will sound terrific even when they test bad). A cheap tester that will uncover gross problems (dead tubes, shorted tubes) may be all one really needs. If you intend to buy and sell on line a lot, you may need a better tester.