I've only played one game of Modern - and really it was only half a game as I subbed in for PE, but I think its really flexible in terms of alliances. Because you can build anywhere, not just your home centers, you can make some seemingly inorganic alliances work.
For example, PE as RUS attacked Ukraine early in this game:
gameID=185867.
When I subbed in, Ukraine had already lost 3 of his 4 home centers but was actively helping RUS and remaining useful.
By the end he was included in the draw as a strong alliance was formed, even with UKR basically losing all his home centers right off the bat.
Overall, RUS does look tough because of having many fronts, and the possibility of getting held to no builds. But to me when you are in that situation, the key is to be the driving force behind a plan. If you are passive in your scheming, you will get the short end of the stick, and the short end of the stick looks really bad as RUS.