I've read in here that the look alike are not much better than just using a set top box.
I have the SM-3500, it's been out two years or so. There has only been one software update since the original with minor improvements.
What meter do you have now? If you are doing mostly Glory star installs a First Strike or comparable should do fine, maybe easier.
The 3500 is a great tool for the advanced hobbyist especially for finding a new sat you have little info about. The spectrum analyzer screen is fast and responsive to peak in your dish. All the TPs on a given sat will peak at the same time across the screen, not much point in trying to look at one particular signal.
As far as identifying a type of signal, I've only learned to spot what a S-2 TP looks like compared to the DVB-S ones, and Dish Net/DTV are easy to ID by the shape of the waveforms.
I paid $600 for mine two years ago, they are now down under $400, a nice price for the hobbyist who has to have everything.