Cons of spurs:
- Learning curve
- Risk of gaff out/cutting yourself
- Don't work will with Ring style platform
I almost sold my spurs after the first few practice sessions. I HATED them. Absolutely HATED THEM. I felt super awkward and totally unsafe. I couldn't get above 5 or 6 feet off the ground. However, I kept at it and after 3 or 4 practice sessions, I felt confident enough to climb to hunting height. But even then it was hard work. It wasn't until I really got confident with them and figured out how to position my body that they started working really well for me. It was probably a full season or so of sticking with it and dedicating myself to learning it. Most guys aren't willing to try that hard.
I also went through the climb down/rappel down debate. I rappelled for a full season before I finally got so annoyed with rope management that I went back to climbing down. A pivot style platform like the Klemz or Predator makes a HUGE difference in taking the spurs off/on at hunting height.
Now, 3 seasons later. WOW! Climbing down is actually easier than climbing up. I've found that if you go really slow and make deliberate movements, your risk goes way down. I usually take about 5 minutes to climb a tree to 25ish feet. I could do it in 90 seconds, but I choose to go really slowly, pay attention to every move, and take breaks to stay focused.
Sure, an accident could happen, but if you're practiced and focused, I think spurs are as safe as any other climbing method.