I'd disagree. I use my Kestrel all the time. For your distances (inside 300m) it might not be that crucial but if you're learning to read the wind, it certainly helps you put a number to what you are seeing and what you are feeling, with regards to wind strength. A Kestrel will enable you to learn to assign a wind value to what you are seeing in terms of flags fluttering, branches/leaves swaying, etc that you can then relate to whatever wind holds you've calculated with a ballistics app. That way you're actually repeatably learning to read the wind instead of ball-parking it. Some people even suggest bringing your wind meter along with you on a daily basis and trying to put a number to the wind that you feel and then verifying it with the Kestrel, so as to better learn what a certain wind value feels like (The Wind Book for Rifle Shooters by Linda Miller and Keith Cunningham promotes this)
Also, I use density altitude for both my ballistic app (Ballistic AE) and my range cards. As distance increases, having accurate environmental is crucial for making (hopefully 1st round) hits. For instance, today I was shooting at my spot at 830 yards with a DA of 600m and a temp of 10C. My elevation was 8.6 mils. The last time I was there, the DA was 1240m and the temp 27C for an elevation reading of 8.2 mils. That's approximately a 12" difference in elevation. Had I used the same dope that I did last time, I would've entirely missed the 2/3 IPSC (12"x19") that I was shooting at! So like anything, it depends what you're trying to do but I do think it's an invaluable tool, just make sure you get one that does density altitude, the ones with built in ballistics like the Applied Ballistics ones are nice (and I want one) but you can get by with a Kestrel 4000 and a ballistics app on your phone. My 0.02
