As I mentioned before, the latest MyTouch devices simply are not good enough to be considered successors to the MyTouch 4G line. But this one is better enough to be a nice move up from the MyTouch 4G Slide.
Surprise, surprise: Samsung Galaxy S Relay 4G to hit T-Mobile with S4 CPU after all
T-Mobile product page, Samsung Galaxy S® Relay 4G
It has a better processor, larger screen, ICS and even HDMI out via MHL cable capability. It is beleived it will have 4GB of internal storage + a MicroSD slot and 1GB of RAM.
Now keep in mind folks, this device won't be picked up by many if any other carriers. So odds are that it won't be getting a lot of attention for upgrades, since there won't be lots of buyers. So if you buy, buy for what it is now and it is better than the MT4GS. There are not many options when it comes to devices with a keyboard.