There are plenty of variations between that and the Grr-ripper to avoid any sort of design patent issues.

It looks like Micro Jig owns the utility patent on it, though.  So the form and function is what matter.

The original patent was set to expire in June, 2021, but it appears that it was extended until August, 2022.

I am not sure if it is, but it sure looks the same as the baseplate that comes with their circle cutting jig (which is quite OK). I had to adapt that one to fit my OF1400 (added just one hole if memory serves me right).

If you want a baseplate that fits the OF1400 out of the box, I bought one from Trent than does so nicely. I'd have to look up the product code though.

You can be sure that Wolfcraft will be hard on their heels with their own version.

By and large Milescraft products have been entirely satisfactory and seem to be well-thought-out and well-made.

They have molds built, so they will not invest in items that don't have significant quantities involved.

I have the original and I have found it less than satisfactory.   Sawdust reduces the coefficient of friction between the rubber and the wood to the extent that it becomes difficult to push the wood forward. 

Also, I am avoiding any type of push stick/push block made from plastic.  The saw blade will grab plastic and kick back.  My  push blocks made from MDF do not display that characteristic.

I prefer to make sacrificial push blocks out of scrap mdf for narrow pieces.  But that has its limitations too.

I love my Grr-rippers. Early on I found them difficult to get used to, but with a little practice, I eventually found them invaluable on certain cuts. They do start out very grabby and that’s hard to get used to and over time and usage they do get less grabby and it is easily remedied with a quick cleaning with alcohol. The tunnel does not bother me at all, again, it’s just very counter intuitive and something to get used to. I don’t use them for every cut on the table saw by any means but for certain cuts they are really great!

I used to use one of these push sticks.  Snip.

This kind of push sticks, except for side pushes, is a potential safety trap because it focuses the pressure on the end of a stock, increasing the chances of steering the work (the front end) away from the saw fence and hence kickback. I use shop-made push shoes only, like this:
https://www.leevalley.com/en-ca/shop/tools/power-tool-accessories/safety/push-sticks-and-blocks/30067-dual-tread-push-stick?item=03J7550