Probably not enough information to answer this question here, but...
1. the new pricing models sounds like the monthly charge will be variable and unknown. Some buyers won't like this (eg if you're B2B, they won't be able to budget for your costs)
2. Have customers asked for this? Therein, may lie the answer to your conversion rate question
3. There is no rule that says you have to have one pricing model. Launch a secondary model and let the customer choose. You could even consider framing one as a decoy?
Have to chat further if you're interested
Jon Manning