when I first did a map with pack size, I died a lot. 1 vs. 10-20 monsters? so unfair! eventually, I learned how to craft a little better, and it was the monster turn to say 'nice try, loser!'. I had so much to learn. so I stayed away from pack size maps.
now I am doing better, and am beginning to see the good side of using pack size maps.
when I was Ascending for my Perks, pack size maps gave me more monsters to get experience from, and that is a good thing. but after I got my sixth Perk, I stopped using pack size maps, because I decided to see how far I could climb, and I started dying again.
recently, I started using pack size maps again, because I recently went on one just for a change of pace, and all the loot! my thumbs are hurting again from clearing out my bags, and my gold is going up faster than it was before, and my Feats are turning over faster again.
for those of you who don't know, pack size maps give a minimum of +50% more monsters to a maximum of +150% more monsters. that is a lot of extra experience and loot. it also mean a lot of extra fighting. all those extra monster will find the weaknesses in your build, so that is a good thing, but also very frustrating, because when they find your weaknesses, that usually means you're dead. that just means it is a good time to craft your build to be better than it was before.
having a ton of monsters trying to put your head on their trophy wall sounds like a Bad Idea, but if you can defeat them instead, then you have an Opportunity to get a bunch of loot to make awesome gear with.