I think you can wear whatever colour you want to.
Some will look more "natural" because the undertone will work with your skintone, and some will look more like a statement colour because the undertone will work against your skintone. I think both look amazing.
I'm fair with warm undertones (meaning my skin is more yellow than pink), and I find that blue-toned/cool reds look like a statement, whereas a warmer/yellow-toned red look more natural on me.
Same goes for berry tones.
Blue-toned/cooler lipsticks tend to make teeth look whiter (but it can also get too cool IMO which makes teeth look more yellow) and yellow-toned/warmer lipsticks tend to make teeth look more yellow.
Mac usually offer really good service IMO, and they always offer to apply or sanitise the lipstick. There's nothing wrong with saying that you just want to think about it/wear it for a bit/want to look at it in other light and come back later.
You could bring a picture of a lipstick colour you're interested in or a description, and let them pick some - or just have a look yourself.
I recently bought Mac D for Danger which I find quite a wearable berry tone. I wear it normally and sheered out, and both look great IMO.
I used to wear Tom Ford Black Orchid a lot, but I actually think Mac Media is very similar and lasts longer. The Tom Ford lipstick just didn't last very long and was patchy - but the colour was lovely and definitely a statement colour on me.
The good thing about classic lipstick formulas is that you can sheer it out by wearing a thinner layer (and adding a lip balm if you want), or you can wear it normally to get the full colour payoff - so if you end up with a too strong colour, you can still get some use out of it.