If you're only going to service a few second stages every year or so, no-just get the cheap one that attaches to a bc hose. As Cave Eagle said the expensive one is just a nice to have or for a work bench. If you're going to make a hobby of buying used gear and will find yourself servicing quite a few second stages a year-yes, get a good inline adjusting tool.
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If you like tools and gadgets, Hell yeah! Treat yourself. Merry Christmas!
Edit: Another very handy "tool" is an inline shut off valve. Attach it to the hose just upstream of your second stage (if not using an inline adjuster) or upstream of an inline adjuster. The reason is to save most of the gas in system.
DGX Inline Shutoff Valve: 9/16-Inch M = 9/16-Inch F