I want to replace my MRF-260 with MRX-1 for now and later on purchase the ipad license.

1) Can I use an MRX-1 IP basestation without connecting to the ethernet?

2) If i can use it without connecting to ethernet, does it require a "RFX-250" similar to MRF-350?

3) Can I use a MRF-350 without RFX-250 antenna?

My assumption is that MRX-1 will work similar to MRF-260 when I do not connect to ethernet port and do not need any additional accessories

You will need to connect to your network to program the MRX-1......so I guess the answer is "no" to your 1st question!

Not sure if it will work after it is programmed and then disconnected from the network? Maybe someone else has tried this?
It obviously will not work with any two-way Wi-Fi remotes which is what it was designed for!

It requires a RFX-250 to use one-way RF narrow band remotes.
It will work like a brick without at least a RFX-250 antenna and network programming!!!!

Yes you can use the mrx-1 without a network connection, but you will need a RFX-250 to make it work. At that point it's basically like your just using a mrf-350. And you cannot use a mrf-350 without the RFX-250.

I'm confused now about the MRX-1.

Is it possible to use the MRX-1 with a by adding an RFX-250 so it receives commands from an IR-based remote, such as the MX-890, MX-880, etc.? In which case, the MRX-1 will work just like an MRF-350?

And if THAT is possible, can you connect the MRX-1 via ethernet, and then use the MX-890 to control a device via IP (such as a Tivo) that is on the same network?

I had hoped I could use the MRX-1 this way, but I read/misread that it ONLY works as part of the MRX-10/Total Control system...

the mrx1 acts just like an mrf350 when you plug in an rfx250.  At that point it can control ir devices via rf from any rf capable urc remote.

the only urc CCP remotes that can take advantage of the RS232, voltage sensors, and relay on the mrx1, is the mx5000, mx6000, kp4000, and mx-ios app.

These remotes send the rs232/voltage/relay data over wifi/ethernet back and forth with the mrx1's ethernet port. 

Since the mx890 doesn't have wifi, it cant do ip control or the rs232/voltage/relay stuff with the mrx1.

the ip control with the mx5000,mx6000,and kp4000 actually happens right on the remote.  You dont even need an mrx1 for ip control with those remotes.  The mx-ios app needs the mrx1 for all control though, since that is where the license code gets programmed.

hope that clears up the capability of an mrx1

Hi Grit,
I tried using the MX-890 with MRX-1 using ethernet. It does not work. Looks like MX-890 is not a wifi or network remote. The network recognized the MRX-1 but looks like MX-890 does not send signals via wifi.
So I removed the ethernet connection and connected RFX-250 and using the MRX-1. (It works similar to MRF-350 as mentioned above). I am happy to use this for now so I can upgrade to iPad license in future.

The MX890 is a IR/RF remote, not wifi. If you purchase an iPad license in the future, keep the MX890 around. While having the program on an iPad or iPod/iPhone is nice, it makes for a horrible main remote.