yea you get some air into the system by disconnecting the abs module.. i dont know that its 100% necessary.. but its a pretty easy process and needs to be done as regular preventative maintenance every couple years anyway so might as well (i bought 48oz of brake fluid.. maybe used 32oz of it.. and it only cost me 10 bucks)
i dont really feel much difference during daily driving, i did take it down some gravel roads and gave the abs a good workout.. its definitely a different feel when stopping on loose pack (snow, wet leaves, gravel) felt a little slower there.. but more controlled.. but my normal commute to work.. theres surprisingly little difference in how it feels