This is really context dependent. If you are flying MDW-DAL, intra-TX, or similar elite heavy route, you will see a big difference in boarding position. However, systemwide (outside the WN focus cities) Southwest just does not have that many elites. I am A-List (not Preferred) and I routinely get numbers like A-17 and A-18. I took a recent 4-segment roundtrip and the worst position I got was A-26. I sat in the exit row on all 4 segments.

So it really comes down to the 100% vs 25% point bonus. The good news is that it's relatively easy to determine a cash value for RR points, so it's a simple matter of whether the cost to obtain ALP is more or less than the additional RR points you expect to receive next year.