I see where this is going and I just want to add that you CAN open with anything the importance of the opener is the way you deliver it.
IF you control your Body language, Voice, (etc...) any opener could work for you.
When a guy (with "I JUST WANT TO FUCK" written in his forehead) approach a set and says want a drink, girls will say yeah , why not... a free drink, but when they get the drink they will disappear and say thanks. In the other hand you have this smooth guy... with great personality and an excellent body language and he is talking to the bar tender when 2 girls sit next to them , he turn his head around and says in a deep voice : HEY want a drink ...

See the difference...
In my opinion ;
Disadvantages: I don't like spending some money only to know persons , I think we have another openers that will work and you will not loose money.
Maybe you telegraph some interest but you can work on your frame, so this don't affect you.
Common, Girls are used to this opener , but once again work on the frame to make it original.
Use it only when you don't have any other opener in mind and your in the mood, otherwise you will be just loosing money.
Advantages: This opener can work, in many situations. Given you a great chance to create some connection (with the toast, etc...) in the first few seconds. A small variation can be made , telling the girls that they should buy the second round later on. (option # 1) If done correctly this opener should work and do its job. Open.
As a second Variation I will comment that YOU SHOULD add a funny DHV story to follow up the toast saying something like ( option #2 ) The other day I was drinking in the bar an a girl approached you asking if she could kiss to make her BF jealous... etc just add a funny interesting story to reach the hook point.
Important things to make the opener work:
BE unique and original, Try to be fresh your buying the girls a drink because your a nice guy, Proper Execution in this opener including nice BL (Body Language) good Voice and tonality to avoid looking as an AFC just trying to hook some girls to have sex.
Long Review of this opener. But this is a controversial one.
Enjoy