At first I was avoiding posting here because my first thought was that you were trying to start trouble but you may just be sincere (at least in an "academic" way trying to see people's choices and rationale) so here is my take on this.
Two similar sized guns, no capacity advantage to the 9mm due to same number of rounds. I still don't see it as clear cut one way or the other.
Both are very capable calibers. I think all the major calibers (9mm and up for auto calibers) in quality premium defensive loadings are very similar in capability. Yes, there may be small differences, but are the small differences outweighed by other considerations? Maybe. It is true that 9mm may have a power advantage over .45acp in the smallest barrels since the .45 drops off faster out of small barrels and 9mm doesn't need much barrel length to achieve its top power. However, your two choices are long enough I don't think that is a factor, and without that the .45 (again assuming good defensive ammo) has a
slight advantage (for the major advantage of the old reputation you need to use ball ammo which isn't well suited to self defense anyway)- but again that is only in power.
Other considerations I think can make the real difference.
As you know, while it is valuable to practice your accuracy generally the most valuable practice and training is the training you do with the gun you actually use for self defense. Unless you are rich or reload most people can afford to do a lot more practice with the 9mm. If you can't afford to practice as much (or very close to it) with the .45acp then you should consider staying with the 9mm.
Weight? The LDA is heavier (probably significantly so). Are you sure you are comfortable with its weight? Would it affect your carry style, carry location, or even how often you'd carry your main gun?
Familiarity. Which are you more familiar with? In this case, since you've had the 3913 for some time, and you have three of them
, that has the clear advantage here. If you want to use the LDA I would keep using the 3913 for a while and get a few months more practice w/ the LDA first.
Manual of arms (related to above). These two are very different and to top it off you occasionally use a snub as well. The LDA has a light enough trigger that, just like a SA, I would never consider using it without the safety. Do you use the safety on the 3913 or do you decock it and use the long DA first trigger pull as your safety (point and shoot)? Either way the transition to the LDA could get you in trouble in a self defense situation. The safeties work in opposite directions so you could find yourself trying to push the safety in the wrong direction to disengage it in a high stress SD situation (even with a lot of practice you still have, what, years of practice with the other system to overcome and the chance of reverting to that under stress is there). If you are used to point and shoot (if you decock and then disengage the safety in the S&W) then you may end up forgetting to disengage the safety in a high stress defensive situation (again, even with a lot of practice with the new system there is the chance of reverting to the old system under stress). Also, the point and shoot option on the S&W is especially valuable since you sometimes switch off to a snub (the same manual of arms is a very valuable characteristic).
Reliability? Since you've had about 500 good rounds out of the LDA but some trouble in the first 200 it is up to you. 500 is pretty good w/out a hiccup. However, compared to what in the S&W, how many rounds w/out a hiccup? I do know the S&W is generally more reliable, but once you have the gun each one is different and your LDA may be great.
Which platform do you prefer? I love 1911s but I also love S&W autos (they have grown on me and I can't wait to get one). Which do you like better? We see which you are more familiar with, but caliber independent would you still be thinking about switching? If yes, train and develop the LDA familiarity and switch (assuming the other criteria I've mentioned point that way). If no, then you may want to stay w/ the 3913.
To me the number one criteria here are (in order): reliability, whether you can afford to practice enough with the .45, which platform you are most used to and keeping as consistent as possible a manual or arms are about equal (both can be addressed w/ more practice though), which you like better, everything else. Given that, and your degree of familiarity with the S&W and its manual of arms, if you really want to switch to .45acp I'd strongly suggest getting a gun closer to what you are already familiar with (S&W or other traditional DA auto, followed by DAO since that would be the least adjustment, and last a SA or LDA type action).
Remeber, we aren't talking .45acp JHPs or 9mm ball, ball in both or .32acp v. 45acp. We are talking about two calibers where there is a difference in power, but not a huge one. When they are relatively close you really need to look at other criteria other than just power (how many other issues do you decide what to buy/use based on only one out of several possible criteria).