According to Nagarjuna, (and others in Madhyamaka and Zen), the relative truth and ultimate truth are interdependent and both are necessary, and it is the ultimate truth that leads you to realizing nirvana! See you there !
Sooooooo.... true! BUT, this is no way means that relative truth IS ultimate truth. Coz when you say that Copperfield and the Karmapa are the same, at the relative level, then you truly have your head lodged up your butt coz at the relative level, quite obviously to anybody, with even a mg of grey matter, they are not. Now if you talk at the absoltue level, of course they are the same. But at the ultimate level Charles Manson is the same as Gandhi, a turd is the same as a diamond, nirvana is the same as samsara.
Unfortunately though the relative level comes along and you have to make decisions like: is killing good or bad? Is lying wholesome or unwholesome? should I shag my best freinds girlfriend or not, etc...
Now if you are a Buddha, a Bodhisattva or even a plain old Mahasiddha obviously your reality does not abide by these rules. But I am going to hazard a guess and say that you are none of the abovementioned. That makes you a common everyday schmuck like me, and we common everyday schmucks have to say that the Karmapa is not an illusionist and that david copperfield is not an enlightened being (either that or go for therapy or heavy sedation).
PS May I be so bold as to draw your attention to this post viewtopic.php?f=40&t=4101&start=20#p44607