To get clear, easier adding of tags is my absolute top priority for GTDNext. 
Here is a list of the solutions we have discussed so far. I have put them into order of priority:
#1. User-defined hotkeys (my personal favourite solution!)
Advantages:
- No need to take your hands off they keyboard ==> much, MUCH faster entry!
- Saves precious screen space
Disadvantages:
- Less obvious to new users.
- User would need to set up and learn their own shortcuts
==> Steeper learning curve
#2. 'Paint' tags onto tasks
Advantage:
Easy to apply one tag onto multiple tasks
Disadvantages:
Unusual and less obvious.
User might keep painting by mistake ==> would need to make sure the paint mode can be turned off easily (e.g. hit Esc?)
#3. Modifier key + click on inline filters
Advantage:
- Saves screen space
Disadvantage:
- Requires use of mouse ==> slower than #1
- Slightly slower because you have use the mouse
- Less obvious so steeper learning curve
#4. Drag tag name onto a task
Advantage:
- Saves screen space
- Slightly more obvious than #2
Disadvantages:
- Requires use of mouse ==> slower than #1
- Slightly slower because you have use the mouse
- Less obvious so steeper learning curve
#5. @jweed71's additional buttons
Advantage:
- Very obvious, so obvious & easy to learn
Disadvantages:
- Wastes precious screen space
- Requires the use of a mouse, so slower than #1
Summary
I have put the above into priority order with #1 being my personal favourite solution, and #5 being my least favourite solution. I hope that makes sense.
J
