Critical Damage%

What is the difference between cd8%, cd9%, and cd10% if my str is 250(bow)? and if my str is my main stat(hb/2h)?
Also, what is the worst outcome if a gamble stat on armor with an 87% success rate fails? Planning to stat my crafted adv garbs with dte but I only have 6 of them so can't risk it that much.

Here's the formula I will use in case it is needed.

Armor - Potential: 46
#1. Critical Damage % +4 (6pot)
#2. Critical Damage +1 (3pot)
#3. Critical Rate +1 (2pot)
#4. MATK % -11 Magic Pierce % -5 Accuracy -12 Accuracy % -5 (464pot)
#5. Critical Rate +1 (x19) (445pot)
#6. Critical Damage % +4 Critical Damage +19 % stronger against Fire +20 (-104pot)
Success Rate: 100%

With cd9%, the success rate will become 96% and 87% with cd10%.

Thanks for the answer/s!

 

cd% multiplies the critical damage multiplier, which is "(150+(STR/5))/100".