They do make a difference (just not in modern raids). I often spend time in older content where the benefits are noticed more easily. One specific case is using my AE snare, which is used when powerleveling. It used to land on me and overwrite SoW fairly often. Very rarely the case these days. This weekend my alt guild raided Deathknell. After the first event, there was a major difference between heroic toons with 450 alcohol tolerance and normal toons with under 250 alcohol tolerance. It's not exactly a resist stat, but it's treated the same way in some events (I think it's part of the berserker 2.0 epic) and it's a very real advantage.
I feel this burden of proof belongs to you. You can claim there is no noticable difference but offer no proof to show. Somehow I think this is going to be a hard one to prove one way or the other. The bottom line is this. Most top tier guilds require you to have the trials and the DON progression done. If you do not have it done, then they are not going to take you, unless YOU can show it is not needed. Do you argue with the sign at the carnival that says you must be this tall to ride this ride, simply because you feel it is an arbitrary useless rule in place. Do the trials and progression or don’t that is your choice, however your mileage may vary.
Bottom line, I was curious if someone knows if the additional +50 resist modifiers make a noticable difference in current content. You don't know the answer. It's fine.
Higher resist wont be a bad thing , but some spells can't be resisted anyway ,so for that it wont matter ... DoN also give you higher Mana and HP buy 1 or 2 percent , So doing DoN is never a bad thing .... Yi Min