PDS vs PDMS

Here's the situation, our client specs requires or recommends to use PDS and our detailed design contractor prefers PDMS. I know the arguments about which is easier to use and all that stuff. What I am thinking now is since we don't normally give the native file of the 3D model (PDS/PDMS) and the client is only getting the bill of materials (BOM) and piping and structural drawings, I would let our detailed design contractor use PDMS and, obviously, I would disclose this to the client. Does this make sense or am I missing something? Why would the client care the software I used to generate the information they need? Thanks,in advance, for all your response.

In my experience we always hand a copy of the model over to the client as a deliverable at the end of the job.
I would think that there is some reason that the client has specified PDS. Possibly so they can have it if in the future they want to do a revamp to that unit.

First, thank you for your replies.

"Our client" = refers to end user &/or EPC. At this stage in the proposal, I still don't know the commercial aspect. Sometimes we end up with the end user as the client sometimes its the EPC.

"detailed design contractor" = sub-contractor

I know that if its required then we have no choice but to use PDS. However, our sales people want to write an exception if we(us and sub-contractor) can use PDMS since we are not giving the client the native files. Only the 3D model will be given. Now, I wanted to know if there are other technical reasoning to prevent us from doing this. Like, how will the 3D model made from PDMS going to affect their future plans. I am only familiar with using the software. I don't have enough knowledge on the administration stuff.

Thanks!