LM5017: The different Ton between original COT control mode & D-CAP control mode

Hi team,

In LM5017 (COT control mode) datasheet , about 'Ton' it says as below. It's inversely proportional to the Vin.

In TPS53219A (D-CAP control mode)datasheet, about 'Ton' it says as below, it's related with Vin and Vout by feed-forwarding.

My question is 

1).The 'Ton' in D-CAP is extra related with Vout, so what advantage it can bring over the COT control mode? Does it make a more fixed frequency shift than COT over wide Vin and Vout range? 

2) Are there any other difference between original COT and D-CAP control mode? What more advantages does D-CAP have over COT? 

Thanks!

Best regards,

Victoria