The overhaul - which would include about 160,000 people shunted from the $56-billion-a-year scheme to separate supports run by the states - could also undermine Australia's human rights obligations, the disability discrimination commissioner has warned.
Actor and disability advocate Hannah Diviney warned the legislation's consequences could be catastrophic, with people losing support they rely on to live their day-to-day lives.
"When disabled people die as a direct result of this bill - and they will - their blood will be on your hands," Ms Diviney, who has cerebral palsy and uses a wheelchair, told the committee on Wednesday.
"How do I know people will die? Because you have made it impossible for them to live in so many ways."
Advocates say the reforms could strip away supports which disabled people use to work and socialise and put more pressure on family carers.
Australia's disability discrimination commissioner Rosemary Kayess echoed those concerns, warning the "structural shift" in support failed to account for the ways in which disabled people live.
"This bill is suggesting that they can abstract out a person's impairment and just provide supports that relate only to that impairment," Ms Kayess told the inquiry.
"Someone's circumstances and what somebody wants to do and does do on a day-to-day basis is irrelevant."
Disability groups have warned the three-day senate inquiry was not enough to reasonably interrogate a huge swathe of proposed changes and called for a six-month delay to ensure proper oversight.
"The systems aren't ready. If the systems aren't ready for reform, then there should be no transition," Australian Autism Alliance co-chair Jenny Karavolos said.
"Yes, financial stability matters. But financial stability alone cannot tell parliament whether reforms will succeed for the people expected to live with (the) consequences. Cost tells only half the story."
While the opposition has previously expressed broad support for reducing NDIS costs, it has raised concerns about the impact of the proposed changes.
Coalition and Greens MPs remain in talks to delay the reforms by extending the current inquiry.
"This is more or less a legislative god power that will enable the minister of the day to shape and reshape the lives of disabled people as he or she may see fit," Greens NDIS spokesman Jordon Steele-John told reporters in Canberra on Wednesday.
The opposition is also threatening to hold the bill hostage to gain political leverage on unrelated reforms to tax on investments.