Originally Posted by IsoAcoustics
The GAIA perform well up to the specified weight limits, but once you are within 10% of the weight limit, we recommend using the next size up for best results. We do not recommend exceeding the weight limits of the GAIA’s or GAIA-TITAN’s.
So when selecting model, stay within 90% of the weight limit for best results. At least this is how I interpret their recommendation.
We also have to account for some speakers only using 3 rather than 4, so need to subtract that from the weight limit as well.

Example:
DSP80000SE, 105kg
Gaia Theis 3 units within 90% of weight range. 145kg -25%, -10% = 97,88kg
Gaia Rhea 3 units within 90% of weight range. 190kg -25%, -10% = 128kg

Proper Gaia Titan version for DSP8000SE is then Gaia Rhea.

DSP7200SE, 55kg
Gaia I 3 units within 90% of weight range. 100kg -25%, -10% =67,5kg
Gaia II 3 units within 90% of weight range. 55kg -25%, -10% = 37,1kg

Proper Gaia version for DSP7200SE is then Gaia I.