I posted these issues elsewhere, but I think I should mention them here too. There are quite a few drawbacks to using this setup:

[s]- You get less macro space for the actual casting:
To overcome this you you can install an addon that makes macro space unlimited but which might not work anymore once the macros become server-side in WOTLK.[/s] [edit] solved by a /click macro
- You can't use modifiers for combining spells underneath one button:
Because these modifiers are used already (thus you get less buttons available that you can use for other class types in your group). For example: You can't make a macro that has Lightning Bolt underneath a button that fires a Chain Lightning if you press shift together with that button.
- Your group is not flexible anymore:
You can't just put any character in your team and have a go with that same team, because the names of your party members are hardcoded in your macros.
- For casting with anything but the standard toon you have to constantly press at least 1 or 2 modifiers:
This is highly annoying and makes casting slower and makes less buttons available for you to bind to an action, simply because you can't reach them with one hand in combination with pressing one or more modifiers.
This is especially a problem as you need a macro for each spell, as you can't use the modifiers for putting multiple spells in 1 macro.