The SGX is great the only con is that you need to pay a yearly membership fee. As for people walking the courses that is true. The break of the greens isn't as great as people think. Unless you are a tour pro, you will most likely not be consistently hitting greens never mind certain positions on the greens. As for lasers, the new ones are fantastic, the only thing is it takes a bit more time to look through the scope press the button and get the yardage. But it is great that the more pricey ones give slope. (the good) Lasers are a bit more expensive than gps' . The new lasers do not need the reflective surface to bounce back light, now you can point it at a tree and it still works. The Bushnell's are a good choice but pricey. I own a gps called OnPar, it is a full touchscreen and is water resistant. Its costs around $300 ,with no membership fees. The only thing about gps' they might not have the course you play on.
It is really up to personal preferance.
hope that helps!