Denon 2900 does it. It can be done "on the fly" but there will be a pause in the sound while the player locates the new program on another area/layer of the disc.
Switch from SACD to redbook layer on front panel?
Are there any "universal players" other than the new McIntosh 861 which offer front panel manual switching from CD to SACD two channel, and then to SACD multichannel? I understand from Mac, that this does not require a video monitor, and can be done "on the fly".