..Regardless what you decide, there are a few important things to consider, when reading all the posts from people that claim to have seen 'failures' of lube pumps, and won't use one as a result:
Yes, a lube pump is one more thing that can go wrong. HOWEVER, contrary to what you read from some folks, 99% of the time when/if a Remco lube pump fails, you are NOT going to fry a transmission, as long as everything was initially installed correctly. Worst case, you might be 'inconvenienced' for a while (have to drive toad separately) until issue is resolved, but that is about it.
It is a 'myth' some folks have started, that a Remco pump failure will fry a transmission. Does not really happen anymore, with the new design Remco uses. That 'myth' probably started several years ago back when that was indeed a risk. Its not so much anymore, with the monitor panel/box Remco uses.
Remco provides a monitor/control box for the pump that mounts to dash of your Motorhome. It connects to the lube pump, and to a pressure sensor on output side of the lube pump. If pressure drops, or pump stops (or is not) running, you get a loud beeping and red light coming on to let you know something is wrong. As long as you pull over within a few miles and quit towing until the issue is resolved, you are NOT going to hurt your transmission. Regardless what all the doom-preachers say, haha. :)
Also, something else nobody really talks about, when it comes to a Remco transmission pump: They (Remco) are confident enough in their product, that THEY provide a warranty for your transmission, that will cover the cost of repair/replacement to such for 40,000 miles from the time you install a Remco pump on it. Soo, there is at least some security there, that you will be covered in the case of a total (and highly unlikely) disaster.
To answer your other specific questions: No, Remco pump will NOT necessarily work for any/all automatic transmission vehicles. You'll have to go to their web page and look your specific vehicle up on their web site to see if they have a model that will work for the vehicle you have or are considering.
As to warranty being voided: As I already said, Remco provides their own warranty for their product, and your transmission. However, if you do have a transmission failure, there is the chance that the vehicle manufacturer will use the lube pump as an excuse to refuse to cover the transmission repair. However, I seriously, seriously doubt, all things considered, if this has EVER happened.
We used a Remco lube pump for a while, on a Kia minivan we used to tow. It worked fine for the most part, once we straightened out some mistakes made with installation (dealer that did installation got to take care of those). Ultimately we quit towing that vehicle 'cause we got one that was easier and simpler to tow, a Ford Fusion Hybrid. However, I'd have no problem going with a lube pump again, if we ever wanted to flat tow a vehicle that could not be towed any other way.