This is just plain not true, to quote a few people from that thread that MakeYouMad is linking:
Post
http://www.graffe.com/forums/showthr...l=1#post130936
http://www.graffe.com/forums/showthr...l=1#post130931
All of them talk about resist rates on direct damage spells and the entire thread advocates using lures in place of other direct damage spells because of that reason.
Hell that last quote there is saying that with 170FR and a 7 level gap (he is 54 and the caster is 60) says, "I usually flat out resist 1 in 4 and the rest dont do jack.". How does that sound like anything you are describing?
Also, just for shits if you go with the resist rate that he is describing AND use the numbers derived from another post in that thread (thanks MakeYouMad)
that means that your 612 damage Starfire (because we are nuking ourselves) does 268 on average.
so, your second test resulted in 2760 damage over 20 casts using the current system. Now if you take the 44% reduction in the above post (because we are self casting) and cast a 612 starfire on yourself 15 times (because 1/4 are resisted) you come out with 4039, so with PvP reduction that would be 2666.
That is a difference of 94 damage
over 20 casts. Now keep in mind that this is only applicable IF a 7 level deficit equals 40ish resistance difference in classic...I'd bet it did and then some.
Maybe I failed at the math up above (very possible) or maybe a 7 level difference isn't that big of a deal...or maybe the people in that post are full of shit...I don't know. Otherwise that doesn't seem all that far off.