Normally yeah, but you want tintaforged to proc 5 times, that it's not statiscally probable. AND you will be raiding normal, so for you, a normal raider, hoping to get a upgrade in a LFR raid it's WAAYYY to improbable for you to do that in hopes of finding an upgrade.
Also, legendaries can be acquired from many sources, LFR set gear from just one, that is not a viable comparison. Mainly because everything you do in the world may drop a legendary, so you are working on them without noticing.
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No they dont, set bonuses are not as critical as they were before. You are counting way too much in your luck to get an upgrade in a content that has a reaaaally small chance of rewarding those. Not to mention you are thinking that any set piece from LFR might satisfy you, when in reality you will probably need a specific one.