It will work perfectly if you place the speaker using the shorter IC 18" further out and toe it in three degrees more. ;) Seriously, buy equal length IC's; if you ever rearrange your gear and are short on one IC, you'll kick yourself. Think long term, which for gearheads is six months.
There does not need to be an actual audible difference to be bothersome. If you're asking about it, it's quite possible that it will play on your mind. If you weren't worried, you would likely have purchased them already. As it is, you may obsess over perceived differences. If so, then it's not that much of a bargain when you're ruminating over it all the time. Only you know if it would bother you or not.
FYI, in my office, one run of speaker cable is approx. 6-7' longer than the other. I am absolutely unable to perceive any effects from it. But, I found I had to put the balance control at 9 O'clock. hahahahaha
There does not need to be an actual audible difference to be bothersome. If you're asking about it, it's quite possible that it will play on your mind. If you weren't worried, you would likely have purchased them already. As it is, you may obsess over perceived differences. If so, then it's not that much of a bargain when you're ruminating over it all the time. Only you know if it would bother you or not.
FYI, in my office, one run of speaker cable is approx. 6-7' longer than the other. I am absolutely unable to perceive any effects from it. But, I found I had to put the balance control at 9 O'clock. hahahahaha