I used to not use LR [back when it was version 3], because it was foreign to me, being a PS user from PS5 days. I have PS version CS6 and LR5 and I have to say that I probably use them equally as much.
I don’t agree that you “have” to use PS or LR to be considered a “pro”, but whatever does the job and turns out good a.k.a. pro results.
I think the reason so many photogs use PS and LR as the default standard is that there are so many plugins and customizations that can be added in without destructing the native app. I don’t know how many custom shapes, patterns gradients and styles I have installed that I have collected and bought over the years, but they all seem to work fine and enhance the PS experience. Being that LR can utilize most of the same plugins and add on’s, it just makes sense why you gravitate to using that app over something else.
I had Aperture installed on my Mac before but again the layout of the tools was foreign to me and it slowed my workflow down. Not because of the program, but that I was not used to using the tools. Now a lot of the same plugins will work on Aperture like Nik, but the market for Aperture compared to PS and LR is a drop in the bucket. This is probably due to the fact that Aperture is a Mac only program, but it just does not have the industry draw like another Mac-only program like Final Cut Pro.
EyeDoc – Having SSD’s greatly speeds up the load time for PS and LR, I have one on my MBP and PS loads up fully in less than 30 seconds. I have a feeling that you are right, that eventually the buffer and the shear amount of photo’s will eventually slow the performance aspect down for any app.
For my workflow, if I do portraits with varying scenes, I use LR to render the RAW files so that my white balance and lighting corrections and other adjustments are similar so there is continuity for the same scenes. I usually group sync the like scenes together and make smaller adjustments for those little variances that can pop up from one photo to another.
After that, depending on the intended outcome, I will sometimes use the NIK color FX to bring out the finer details and other stuff then render them in PS with masks if the need arises. This is taking into account that the photo requires all that attention to begin with.