Reply to Traktor s2 emergency backup

Hey guys! I'm believeing of buying an s2 but I found out i can't plug in a backup devise like an iPod or ipad. This scares me because I'm a mobile DJ and if I can't have a back up ready to hit play if my laptop crashes. Is there a solution for this? If not would it be wiser to get the novation twitch cus of the backup? All advise will be greatly appreciated thank you