Thank you in advance for reading my wall of text below.

I’m currently in the process of re-finishing the poured concrete basement in my 1979 Southern New Hampshire home. The basement was previously finished some time in the 1980s, possibly during the original build. There is no insulation underneath the existing slab.

I’m working out how to properly do the insulation down there and have recently been struggling with the best approach for insulating the floor. I have two possible approaches that I’m considering, but have a question about each approach that I haven’t been able to figure out from my research.

My primary limiting factor is total floor stack up thickness. My primary support beam is running through the middle of the finished space and is 76″ off of the concrete floor. Ideally my floor stack up will be under 1.5″ including LVP finished floor, and it almost definitely needs to be under 2″

Approach 1
Lay out Dricore Subfloor R+ panels prior to insulating foundation walls or building. The panels would have a 1″ gap from the foundation walls as outlined by the installation instructions, followed by 2″ rigid foam adhered to the foundation walls. Framed walls would be built on top of the subfloor against the wall insulation. This approach would result in a construction similar to Figure 1 in BA-0309 from Building Science Corporation (see below). My problem with this approach is it leaves the OSB of the subfloor exposed to a 1″ x 1″ channel that I’ve now created around the perimeter which could potentially wick moisture or absorb water vapor. Additionally, the OSB of the panels are now between my floor insulation and my wall insulation, so I wouldn’t have continuous foam throughout the whole basement.

My questions with this approach:
Would you do anything different with the floor-wall insulation joint than what I’ve outlined?
Am I really getting a tangible benefit from having the channels underneath the subfloor?
What’s the risk of water vapor getting through the seams of the subfloor panels and soaking into the OSB?
This approach would require fastening the panels to the concrete floor. Does that increase the chance of water working its way up in to the OSB?

I’ve considered using seam tape to cover the wood edge of the panels that would be exposed to the channel but I haven’t seen anything like this in my research.

https://buildingscience.com/sites/default/files/migrate/pdf/ba-0309_renovating_basements.pdf

Approach 2
0.75″ NGX 250 rigid foam adhered to floor, with 2″ rigid foam on the walls, seam between the two taped. Thinnest possible tongue and groove plywood (Can I even get this in 0.5″ or under?) on top of the floor insulation, floating. Framed walls built on top of plywood subfloor, fastened to subfloor and ceiling joists.

My questions with this approach:
Am I increasing the risk of future flooding or water damage by having rigid foam adhered directly to the concrete floor with no air gap?
Is there any aspect of this approach that you believe is catastrophically incorrect?

Some additional information about my basement:

It has some perimeter drainage under the foundation floor with a single small grate by the bulkhead stairs to provide access to the drain from inside the basement. The drain routes to a covered basin in the corner of the basement which has a gravity drain bringing water out to the public storm sewer. The storm sewer grate in front of my house is below the grade of the basement floor.

There’s no evidence the basement has ever had standing water in it (40+ years with non-pressure treated wood making contact with the floor and carpet installed directly over concrete can attest to that), but of course that doesn’t necessarily guarantee it will never happen.