What are pitfalls of "hard mounting " tranny vs rubber mounts?

so I am at the point in Engine swap that the TR6060 has to fit in the Demon. I have to fabricate the tranny mount and am wondering what is down side of hard bolting the tranny support? I do not have a lot of room to create a vibration pad if you will. I have seen a lot of folks simply make the support bracket and bolt it up, but the factory always provides a rubber mount. Likely for a good reason? Any advice or experience would be greatly appreciated. The engine is a 6.1 Hemi backed with the TR6060. Virtually zero mods with exception of headers and CAI. Daily driver 72 Demon.

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