I export .ai's regularly from XXP and import them into SignLab for sending to the vinyl plotter (cutter)
Of course I make certain that:

• Text is shapes
• Colours are 'spot' colours
• Lines are shapes
• No bitmaps and no bitmap effects

Never had an issue yet.

However, sometimes when a client supplies a file which is a bit iffy - we open the file into CorelDraw and either re save as a supported format or even just copy the vector shapes to the clipboard and paste into SignLab. Signlab will also import PDF when you follow the same rules above as the .ai files (.ai and .pdf are after all very similar)

Your signshop may not be using SignLab for their plotter of course, however it's always best to find out what software they use and which format they prefer to work with.
If they are using Signlab and you want to supply them your file as a .CDL (Signlabs file format) feel free to email me your .ai and I'll convert it for you.