Case1.) If zou take the RXLEV in idle mode and the RXLEVFUL in dedicated mode (call running on hoping trx) with DTX active (you could see DTX activity factor in tems) values are different.
If DTX activity factor will be 0 (or near by) then RXLEVFUL and RXLEVSUB are same.
But in case, if DTX activity factor will be 80%, than RXLEVSUB is correct value and RXLEVFULL is wrong value (for example RXLEVFULL is 15dB below than RXLEVSUB). It is due to different evaluation of measurements.
Case2.) If the call is on BCCH with DTX active, will the value RXLEVFULL will be equal to the RXLEVSUB and RXLEV in Idle mode at the same time. It is due to fact that all TS on BCCH are transmitting on max power (all the time).
In case that no DTX in Downlink than RXLEVFULL = RXLEVSUB = RXLEV in Idle mode.
Of course, Hopping has some gain (2-3dB) and Hopping TRX could be stronger than RXLEV in Idle mode. It depends on environment, if it is open space or dense urban. With EDGE on BCCH there could be also some fluctuation of signal (different type of modulation)