In short, compared to a linear driver you won't see any difference if using a quality driver, besides highly boosted efficiency that is. Also, noise is totally irrelevant here as 1) It should get low pass filtered by the output caps forming an RCL low pass network with the inductor and the diode ESR. 2) even if it isn't It won't affect a thing cause noise is just some minor ringing at the switching waveform that can be caused by a bad power source or a poor quality driver IC but the noise spikes shouldn't have enough energy to do anything really. The only determining factors on a driver are current ripple and rise and fall overshoots and/or regulation errors due to poor component selection.
That is not really true, no matter quality, except if they have a linear output stage, SMPS drivers can't do much about source noise besides utilizing the RCL filter that is formed on their outputs as I mentioned above, by themselves, they have almost 0 db of noise rejection, linear regulators on the other hand do.
My SMPS is indeed a bit noisy, but not horribly bad. I've seen far, far worse! I'm not so sure that I'd like using my switcher for radio operations, or RF sensitive circuits, however. For general electronic gadgets and tinkering... it seems to work quite well and fulfil my basic needs. Perhaps I'm just looking for a good excuse to purchase, or 'build' a good linear power supply. Clean is clean, quiet is quiet and anything else is simply less clean and less quiet! Does it really, truly matter, with laser drivers and laser diodes? Hmm, not sure, however. "It can't hurt!" Before I go shopping for a retail linear system... you wouldn't happen to have a schematic 'roadmap' for a proven, DIY, laser friendly linear system, would you?
Look at the LM317s datasheet (texas instruments version), you should find "Precision Current-Limiter Circuit" listed there.
