I hear ya Art...
What I meant was to get the same candela out put of a light depends on what wavelength you want to use.
A green or red light will need more lumens to reach the same or similar candelas of your white spotlight.
As far as filters, don't use them unless you have no resort.
Adding a filter doesn't change the lightwave output of a bulb.
It literally absorbs all lightwaves but the one it lets thru.
So, a pure red lense will absorb all light of all other wavelengths/colors.
That is why the lense gets hot, and eventualy melts.
It has to do something with the energy it is absorbing. It stores it as heat.
So, the question of filters working well, just depends on how much of that specific wavelength light the original bulb was putting out.
If it doesn't generate much red light, it won't shine very far or bright.
And you will melt the lense.
Same with green or blue.
If shopping for LEDs, the best brightness they can come up with, vs power expended, is "cool white".
Blue isn't very good, red gets a bit better, Cyan is good, and green is very good.
Something to do with the chemical makeup of the LEDs.
A good reference is the LUXEON Rebel...
Just click "expand all" in the "Products" table.
http://www.philipslumileds.com/products/line.cfm?lineId=19
The human eye has trouble with blue light.
That is the reason why the "Royal Blue' is rated not in lumens but power output.