Upgrade MBL 1521/1511F to 1622/1611F - worth it?

Have an MBL Reference system apart from the CD player and DAC. My dealer would let me upgrade and I went to compare the two, but a 30mins session gives you only a limited feel of the differences of course - I thought particularly with SACD you get a bit more depths and transparancey. Wonder if there are people who can share their views - the upgrade is of course not cheap ... Thanks