Dante's Inferno

Using the 'bomb' method most people making short trials are using now, I created bronze, silver, gold and platinum trials that take 6-10 seconds, 6-10 seconds, 12-20 seconds, and 18-30 seconds to finish respectively. They're by my gamertag (lifeexpectancy) and they're named Bronze in 6 to 10 sec, Silver in 6 to 10 sec, Gold in 10 to 20 sec #1-50, and Platinum in 18-30 sec #1-25 i.e. 75 different unique gold/platinum trials all identical for quick work towards your rate 100 achievement.

Simply run up, hit the bomb, and hold block. It explodes killing all enemies and the trial is over lickity split. That way all you have to do is play/rate the 75 I've uploaded and you're 3/4 of the way toward "rate 100". Just replay the same bronze or silver one over and over to get your medals after you've played/rated another 25 community trials. I wish I'd discovered this before I spent 4 hours playing and rating my slower trials! Getting 25 platinum ones done even with the time it takes to go back to the trials list only takes 15-20 minutes now. I estimate 50 gold medals at 20-30 minutes tops. Silver and bronze will be extremely fast because you don't have to exit to the menu to pick another trial.

Use the filters to find the trials made by me (lifeexpectancy) and set 10 at a time as your favorites so that after you finish a trial and it goes back to the list of community trials you can simply press  and switch to the next one you haven't played/rated rather than having to set up the filters all over again. Rinse and repeat until you've rated my 75 trials (or just 60 of them, then replay the gold for your last 15 medals if you intend on doing all 40 EA trials and rating those). Then it's a matter of simply replaying the same trial for the rest of your bronze/silver medals. I estimate you can finish all 3 achievements in 2 hours absolute max now using these faster trials.