this has been an age old discussion (that normally ends in dispute) since the first Ti yoyos hit the scene.
for the sake of both parties, i will present both as unbiased as possible
AGAINST sparking: my yoyo was made to be an engineering miracle and i thoroughly appreciate this to the point that i am greatly against damaging it. i understand that damaging it produces sparks, which to some may be interesting, but i can find cheaper ways to obtain this thrill without damaging my investments. my titanium yoyo is a collectable that should be kept safe.
FOR sparking: my yoyo was made for the sole purpose of being enjoyed. titanium offers the ability to spark. while this may potentially damage the yoyo, i do not buy my toys to sit them on a shelf and watch them. if my yoyo can spark, i would be denying it part of its potential to not spark it. my titanium yoyo is a toy that offers a feature i feel should be utilized.
although i can see both sides, i lean SLIGHTLY towards spark over no spark. i can understand the collectors side, but there are thousands of yoyos that i could collect that dont spark. i compare this to buying a computer but not using it for the internet. while you still have a great resource tool and it is much less susceptible to damage, you are not using it to its fullest potential.
in the end the choice is yours. they are your toys. enjoy them however you want.