Hi Al,
Agree with everything that's been said thus far, and we also recently implemented QR codes in our design, which has made it even more streamlined for mobile.
We have always had two barcodes printed on our PAHT, one made up of the ticket number (so there's a backup) and one made up of the N-Scan number (a combination of order/seat/ticket number indicators). We flipped the shorter, ticket number barcode to a QR code and repositioned it at the top of the PDF. This made it much easier for the patrons to open in the right spot, a lot less zooming in and out because the QR codes naturally fit well on mobile screens, and the scanners like the QR codes much more. We still have the longer N-Scan number barcode as the backup.
Good luck (and bring on Apple Wallet/PassWallet down the track!)