I don't know what an aerial round-off series is. So I'm wondering if you need the back tuck to "carry the day" for your beam routine, and leave a good impression on the judges. You also have to consider your own feelings about what you want to get out of your beam routine to fulfill yourself. I personally regard a back tuck as one of the traditional milestone skills on beam that can boost your levels of confidence and self image.
Consider your long term outlook and goals vs. your need for short term rewards and scoring. Maybe you "need" to have a beam routine with as little potential for stress as possible that can get you almost the same score as one that you're stressed out about. Is that .1 really worth it? I think the answer depends on how you feel about the upcoming season, which won't hit the "boiling point" for about five months when you hope to build confidence and momentum going into the six weeks before your post season qualifying at the state meet.
Me personally?.........I'd pack the routine for now, and train like crazy to get it together by the end of January, and then decide if I needed to "adjust" to get through the rest of the season. It's just like the guy who cuts my hair say's....."I cut it a little long 'cuz I can always take a little more off, but I can't put it back on".
The benifit to you is that you can feel even more confident with the skill next year, and there are a handfull of neat combinations you can put together with a back tuck, but to put those combinations together and totally wrap your mind around them, you should have carried the back tuck around 24/7 for a full training cycle.
Have fun figuring it out, and work your tail off to support your decision with a good season.