Sliding table saws are potentially safer in that you can move stock over the blade of the saw without getting your hands near the blade. The same can be done if you have a crosscut sled of course. But then again, a slider is likely to stay calibrated longer and thus is considered superior. Sliders will also allow for mitered cuts a bit easier then a cross cut sled where you might need to make a whole new sled to get the same effect, and the same again for dados. Is it worth the extra hundreds or thousands for a slider though? Well that depends on your budget. If it were me, I wouldn't buy a slider instead of buying another machine... but if I had a crazy high budget and was looking to burn some money I wouldn't hesitate to pickup a slider. I have never used a scoring blade before so I can't speak about that. You would still want a zero clearance insert either way though as it can prevent certain kinds of kickback situations.
The only time I have sent food back was when I ordered a steak and it came out VERY under done (could not have been under heat for more then a single minute) and I had ordered medium. Even then I felt bad about doing it. They put it back on the heat and it came out fine. I have never sent back food for being over cooked and the only time I could imagine ordering something completely different is if I thought the food I was being served was literally unsafe to eat. I have been offered different things before when it was obvious to the waiter that I did not like my dish, but I have never taken them up on it. The way I look at it is that the whole dining experience is a gamble. Frequently you win, but if you lose one you shouldn't blame the restaurant or server because you happened to not like the dish they served. If the quality is not there then you shouldn't have gone to that restaurant, if you don't like that dish then you shouldn't have ordered it. It doesn't mean that you should use your own choices against them in some kind of crazy game of "please the customer or else." And at the end of the meal if I have extra left over I will ask for a box and take it out of the restaurant even if I have no intention of eating it as well. I figure this is just polite as well. And unless the waiter is actively rude I will always tip, even if I don't like my meal. Tip is part of the price of eating out.