If you have trained extensively with iron sights, it will definitely make the transition to the RMR sight system easier and less frustrating in the beginning to use the BUIS and take advantage of muscle memory already developed from thousands of reps presenting the pistol. Just draw and aim as usual with the iron sights and the dot appears. After you get more experience with the RMR system, the BUIS will become less important.
I'd also suggest reading the opinions in the following thread at WarriorTalk.com about the advantages of BUIS with tritium inserts together with the RMR from some operators with great experience and proficiency with the RMR-equipped pistol.
Personally, I have BUIS with tritium front and back with the RMR (RM07) and wouldn't have it any other way on one of my pistols for CCW and home defense.