Field coil speakers: varying Qes

[otto88]

I have some questions about field coil speakers/ Qes trade-offs.

For a given driver where Qes and Qts is much higher, is anything “lost” in the trade-off, or will any other parameters that effects the sonics change?

Eg with the lower Bl, transient performance??

Situation:
I’m seriously considering getting a pair of the Supravox 215-2000 EXC, very expensive but highly recommended by several who I respect and trust. (It’s wide range, but these questions would apply to any field coil speakers) There are two versions:
The standard EXC version with (depending on power supply volts) Qts variable between 0.25 and 0.34. At 9 V it’s 0.31, with a spec of “98 db”.
The open baffle version with much higher Qes. eg at 9 V the Qts is close to 0.8. It’s not listed on the Supravox website and TS parameters aren’t available . . (I believe they have the same efficiency, though am not sure; and I believe they have the same Xmax, but also - not sure)

I’m doing an open baffle, but because I have very good (2 * 12 inch a side) open baffle ‘subs’ which can work well up to 160 Hz, don’t need the extended bass that the higher Q OB version can provide.

I'll be using a SET amp in a large (long) room, so preserving/ high sensitivity is desirable.

Thanks

[otto88]

I've done some searching:

Apparently the high Q version is -1.5 dB than regular version.

Any other likely changes?

Thanks