I've used Pascal, double-frequency YAG, and argon (the latter two with LIO attachments, as well). I agree that you need to be proficient in multiple modalities. You don't know what you're going to end up with in your future practice. Fact is that the predominant laser out there is still, and will be for quite some time, argon. The Pascal is great, but you're going to drop about 90 grand on the low end to get one, whereas you can get a new argon for about 1/3 of that. They're starting to pop up in more academic centers, because OptiMedica gives them a price break. I have to admit it's a good marketing tool: get more docs trained on them, sell more down the road. Nevertheless, not many private practices will be buying them until the price comes down. In the real world, purchases are made based on ROI (return on investment). It's not THAT much more efficient. In my current practice, I use an argon that is about 15 years old, but works fine and has an LIO.
The power settings for PRP will vary considerably, depending on fundus pigmentation and media opacity, but I usually start with 200-300 mW. In residency, I used 0.1-0.15 sec duration, but was recommended in fellowship to drop to 0.05 sec. Nowadays, I sometimes even go as low as 0.07 sec. The power has to come up, but the patient is generally more comfortable with shorter burn durations. I've only blocked a patient once, and it wasn't my choice. One of my attendings in residency insisted. I did the second session without a block, and the patient actually preferred it.
I use a Volk Quadraspheric or a Mainster Widefield, at least for initial PRP. They're good for work from just outside the arcades to past the equator, which is all you really need to start. I set the spot size at around 200 microns, but keep in mind that the lens may change the actual size. The Quad doubles the size; for the Mainster it's just under double. That puts me at around 400 microns actual size. I shift to LIO for more peripheral supplemental PRP.
As far as technique, I usually don't go faster than 0.3 sec on the repeater. Honestly, it's hard to reliably move the beam around much faster than that. If you aren't hitting new sites with each burn, you're not being efficient. If you have a little thumb stick with which to move the beam, you can make numerous burns while holding the lens and slit lamp joystick steady. I don't have one on my current laser, so I've resorted to shifting the lens around slightly on the eye to move the beam. I don't press hard with the lens. That's a good way to make a patient go vaso-vagal on you, and that's just no fun at all. Combined with small movements of the joystick, you can go pretty quickly with the above technique. In a cooperative patient, I can get in 1000 burns in around 15 minutes. I really didn't get up to a good speed until the end of 2nd year of residency (in my program, the bulk of lasers were done in the 2nd year). Just requires some practice. Stick with it.
