It is generally acknowledged that the average external cam QR is not as strong as the average internal cam QR. External cams are now more fashionable for some reason, but Shimano still uses the internal cam, even on their fanciest wheelsets and hubs. I therefore only use internal cam QRs on all our bikes. With a front disc, I think it would be very unwise to use an external cam QR - so go get yourself a good quality Shimano QR!