There is a semi workaround. You can enable tempo for the rig and morph the delay time in note value. This way you don't have the "tape echo like"-effect. For me the result is closer than mixing two delays.
The disadvantage is that the delays will morph in steps and not smooth. Another disadvantage is that moving from a 40ms short slapback to a 550ms, 100% feedback delay is not precise enough. BTW morphing Feedback from 40-125% without enabling "infinite" separately would be likable
You are right, thank you!
Discussion about this feature is continuing in the FR thread Please bring back a delay without doppler effect when changing/morphing delay time aka. Free delay