Are you seriously suggesting that Susato whistles and Susato recorders have different tone qualities? Sheesh. How do you imagine that happening when the only difference between them is where some of the fingerholes are?

Recorders are more accurately in tune than most whistles (for very expensive whistles there is no difference). But the purity of their tone varies a lot. The more expensive a recorder, the more options you get, and I usually have a variety on hand at the same pitch but with different timbres. Complex tone with extraneous partials is usually described as "reediness", and (by sheer linguistic fluke) reediness can help when playing along with free-reeds. The transparent Yamahas are reedier than most basic descants, which is why I pick them as "blending" instruments.

One way to dirty up the tone of a flute is to hum into it, very quietly. These are more extreme versions of the technique, I usually do it far more discreetly and only on a few notes in the tune:

Evelyn Nallen on singing into the recorder
Andras Hodorog, whistle
Andras Hodorog, Moldvai kaval
Nina Perlove on the flute

I've been playing in a session with one or two moothie players for 4 hours a week for the last 20 years, so I've figured out how to blend in by now (or *not* blend in when I need to, for that matter). There are lots of tricks. Practically none of them are specific to the recorder or whistle (or even the ocarina, for that matter).

The instrument that I perceive as having a disconcertingly pure tone is the concertina. Takes a bit of thought to produce a tone that goes with it on a flute-family instrument. But you very rarely hear it without somebody in the room playing a fiddle at the same time, and that makes it easier. It can also be difficult to play a recorder (or a very good whistle) along with a really crap whistle - I will usually either use the humming technique to generate a sort of composite flutey-musette sound or else pick up an instrument in a different octave.