Massachusetts is not part of the Drivers License Compact (DLC) as you noted however they have agreements with most other states to exchange information regarding tickets that licensed drivers receive out of state.

According to the Massachusetts driver's manual, located at the MA Registry of Motor Vehicles (RMV), MA has arranged to share driving record and criminal violation information with other states. The MA RMV does not list which states they hold agreements with so you may want to contact them direct to see if a representative can tell you for certain if Rhode Island and Massachusetts exchange information regarding moving violation convictions.

The RMV driver's manual goes on to say that certain traffic offenses committed by a MA licensed driver in other states will be placed on their MA driving record and treated by the RMV as if the offense had occurred in Massachusetts.

Since the RMV treats most out of state violations as if they occurred in state, then a Rhode Island speeding ticket will likely be treated as if it happened in MA. If this is done, according to the Safe Driver Insurance Plan (SDIP) a minor traffic violation (like speeding) is assessed a 2 point insurance surcharge.

If it is your first minor traffic offense, than it may not since the MA Division of Insurance SDIP information states that there is not an insurance surcharge for a driver's 1st traffic violation.