I may not be an "expert" when it comes to pool tables but I am when it comes to natural stone or slate in this case. The issue isn't necessarily the support the cross members offer over the short term but rather over a long period of time. People have used the term warp when it comes to slate and that's incorrect. The slate will sag or bend slightly if not supported.
Let's imagine this isn't an issue for this table. Does the table play as needed compared to say a Gold Crown? If so, this design could easily be retrofitted to provide that support with little effort and expense. I know they have a showroom so I'm going to go test the rails out in the coming weeks. For $2k ish it looks promising.
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