MLB Saint's invitation on a cheesecake servant with decent damage?

The numbers Zhiroc provided look quite good and do align with the data which Lord Ashura provided (a bit on the lucky side though). As Zhiroc pointed out, I assume that the guide still recommends the 40 AP one since stocking drops and material drops are quite a bit superior. It's also likely that the drop rate for the Event CE is a tiny bit in favour of the 40AP one as well (when you look back at data for previous CE drops). I do think that the guide should mention it, though.

As a sidenote, I would be careful to confirm stuff by trying it just once. Sometimes it can do you harm instead of actually proving something. Do not forget that variance is a thing. Just because the estimated cost for summoning a 5* is at 300 SQ, it doesn't mean your personal experience reflects exactly that number.