Dear Chaitanya,
I’m not familiar with the limitation of BEM at high TSR. Are you referring to the comment regarding the Prandtl tip-loss model on the bottom of 5 of the old AeroDyn Theory Manual: nwtc.nrel.gov/system/files/AD_Theory.pdf? Regardless, we typically enable the Prandtl tip-loss model for all solutions with BEM.
I’m not sure I understand your question regarding DYNIN, but the instability of DYNIN at low wind speeds is discussed briefly in the following forum topic: Dynamic Inflow.
Best regards,