TI RF solution - MSP43x+CC1100 vs. CC1110, toolchain
I used MSP430G2553 and CC1101 for modbus project, Star topology and used a protocol similar to Bluetooth. First I can say that, cc1101 promises 10 dBm output power and -116 dBm receiving Sensitivity for 433 MHz but when you configure data rate and channel spacing it becomes really messy and useless for longrange. Maximum range we got was 120 meters. So if range is a heavy FoM in your project, I suggest you to find another transceiver(We switched to Semtech later). You can do your own research on internet, everbody complains about it.

Secondly, If you are communicating via MODBUS, package delivery time and Datarate should be the last things to worry. I assume you will be working with PLC's, have the slowest queries. I suggest SemTech SX series with MSP432 or any other ultra Low power mC's of ti with EnergyTrace technology. This is only my thought but I think ti has some more way for RF technologies.

Edit: Also Xbee 868LP should not be an option. Design flexibity becomes really important later on in the Process projects.