I raid with mouse over healing macros. You can't make them too complex but you also have to be very aware of the macro sequence priority sequence.
The most reliable mouse over macro is to have mouseover the ONLY option and mouse over the party faceplates (this also works on alliance raids):
The most unreliable way to do a mouse over macro is to have two or more target conditions. The FFXIV macro system doesn't do what you would expect necessarily when casting becomes available and check if there is a mouse over option first and then general heal situation (target or self if you have smart casting enabled). Instead when you use the macro regardless if you can cast or not the macro starts. If casting becomes valid in the middle of macro execution it can skip the mouse over clause and default to healing our target or yourself. This occurs frequently since the Macro system doesn't queue and when using macros you have to spam click to heal effectively. Not a fun implementation./macroicon "Benefic"
/ac "Benefic" <mouse>
The following is a compromise which I use for raiding, solo and general party play. You can use /mlock to force the current macro to finish before another macro can start casting, this avoids weirdness of cutoff macros when spamming. Then you duplicate the scenario which should be checked first. What this does is artificially check the first condition many times, before "risking" checking and executing the secondary condition. This greatly raises the consistency of a mouse over macro with a secondary condition. Also target of target is often the secondary condition you would desire over mouse over, especially if you tend to hold your right mouse button down while moving/dpsing/tankhealing./macroicon "Benefic"
/ac "Benefic" <mouse>
/ac "Benefic"
Anyway those are my thoughts on how to compensate for mouse over healing problems in this game./macroicon "Benefic"
/mlock
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <mouse>
/ac "Benefic" <tt>