Could someone help me with the Pro's and Con's of spending Myth?

[Fendred]

Unless you have extremely little play time, it's way too early to be hording myth.

I can hit myth cap multiple times a day doing hunts.

Um, no. Unless you have obsessively compulsively memorized spawn points, methods of spawning S ranks, and have everyone on your team on the same page, it will take a while to cap using hunts. There is someone who posted he got to 2700 myth in 10 hours. That sounds believable to me. Saying you make that cap multiple times in the same day sounds like a load of crock. Even if you could most would be disinclined to do so for the sheer fact it would bore them to tears. Maybe as a marathon day, but certainly not on a daily basis.

For the new guy: Doing hunts would be great to get a few of the pieces you want, but since you are new to 50 there are a lot more interesting things for you to do than hunts. Try out some of the end game dungeons on duty finder. You'll get myth from doing them and perhaps some decent pieces of equipment as well. You'll quickly gain all ilvl 90 with a mixture of myth and allied seals, so there is no reason to rush. I would try getting in a few hunts to help speed things up.