Hi Potential,
I liked to read your post since the same question popped up in my mind some time ago. I don't know the answer yet but reading MDMA_AcTIvEsTS's reply make me think I know the answer now.
If your are using HCL gas and make very fine bubbles then you have a very good contact of the gas molecules with the freebase and the salt will come out of solution with a minimal amount of HCl used. [I think the better you disperse the bubbles the less volume of gas you need for making the salt since the finer the bubbles the higher their specific surface is]
Of course adding a huge amount of HCl by titration will also form the salt but your environment will contain much more HCl than with the gassing procedure. This could explain the saltier taste, since your MDMA.HCl crystals are contaminated with the excess HCl in solution.
I think it might be interesting to use very pure HCl if you do the titration to have no other contaminants than HCl in your final product.
If you do the titration with HCL, couldn't you wash the salt afterwards to get rid of the excess HCl?
I don't know if the above is correct, since it is just some of my reasoning