Lots of people use hot sauce in their Shimano's, Daiwa's, Abu's, etc. without problem. I use Reel Mechanic's house brand lubes, it comes down to personal preference.
The key to lubing a reel is that all traces of the original oil and grease MUST be gone before proceeding with new lubes. Not a quick wipedown "close enough" deal, it's got to be surgical.
Regarding warranty - As much as automakers want you to buy their lube fluids and filters, they CANNOT deny you warranty coverage as long as what you used was equal to or exceeding their specifications and was done at the proper intervals. In the auto world, for example, oil is classified within a uniform conformity code, which means as long as the brand of oil you choose meets the manufacturer's minimum requirements, you are covered.
That being said, reel lubes are NOT classified the same way, so basically anyone can package what they want and make any number of claims about it. The point is Shimano, Abu, whoever should have the right to determine which lubes go into their reels during the warranty period, because there is no uniformity in the reel lube universe.