What attracts you to Late Rome?

[starman2012]

The East was lucky in that the Sassanids were busy with the Hepathaltites to the East.

Right.

HAd the Sassies launched a major attack at the Same time as Attila's campaign, the Eastern Empire would have gone down the tubes quicker than the west.

Well, a lot would've depended on the state of eastern defenses, and Sassanid objectives. Had the Persians just wanted plunder like Shapur two centuries earlier, or Attila at the same time, the East would've been ravaged much more extensively but, assuming minimal permanent loss of territory, it might still have survived. (Look at the beating the whole eastern part of the empire took in mid third century.) It probably wouldn't have been able to underwrite the campaign of 468 but that failed anyway...