When I first started crimping I wasn't too knowledgable about it.
I picked up a pair of point to cup crimpers, round sleeves and 135lb. 7 strand coated cable.
I found that its just about impossible to keep the wires from crossing when doing a fair to tight loop with the round sleeves.
Did more research and found that the double barrel sleeves would eliminate this problem. Found that cup to cup crimpers would be necessary for the double barrels so picked up those crimpers as well.
Nailed it, found that this is the way to go and im sure most would agree.
I made the switch from 7strand to to AFW's 49 strand. The suff is so much softer and limper. Quality stuff as well.
Ill run the 480lb. in 2 foot leaders or 6 ft. depending if im casting off the ground or wading out casting.
Ive had no issues, caught large bats, leos and a 7gill. Ive put even more pressure on the crimped leaders in the backyard hanging weights from them.
I like AFW's website, when you order wire from them they will tell you what size crimps to get. Other than that, rule of thumb is to get a sleeve that fits snug to your wire.
As far as crimping mono, I don't.. I can tie up to 130 mono so didn't see why I should crimp it. If you do decide to crimp it, use aluminum sleeves.