The transmission is actually very easy to work on, but you will need a press to get the gears apart.
As for the stock shifter, it is actually a very good shifter. The cost to rebuild the stock unit is about $45 US, much cheaper than the $170 for the B&M. The B&M will not change the hard to shift problems, in fact it will make them worse since it has a shorter throw. As for a "rubbery" feel, well, the only "rubber" in it is in the shifter handle. The Ripper does not include a new handle, so you will have to buy that extra anyhow. You could put a solid handle on your stock rebuilt shifter and eliminate any "rubberiness" that way.
As for the grinding gears problem, you have bad syncros. Period. You don't usually need to replace the whole assembly (~$180 ea), besides they are discontinued anyhow. All you generally need to replace are the syncro rings themselves. (~$30 ea). When you pay $800 or more for a rebuild, you are not getting new assemblies either.