With the LEDs being WHITE, you'll notice more purer colours of your plastics, as opposed to the typical YELLOW (warm) light from bulbs.
Also to note, in machines where GI lamps are DIMMED, the LEDs will stay constantly BRIGHT until the dimming voltage is low enough for the LED to turn OFF, so you'll lose your Dimming effects, it'll become more of a blink effect.
These ultra-bright LEDs are VERY efficient, and you really need to pulse-width control them for dimming effects.
Also beware of LED focal point, narrow beams versus wide beam, this may affect the mounting distance under the Playfield, otherwise you get a whole bunch of hot dots, instead of nicely illuminated plastics.
Some LEDs may even require a softening filter between the LED and the plastic. using something as simple as tracing paper (oven baking paper) will do...time to experiment.
Something to consider, depending on what machine you fit LEDs into....
my 2 cents....
MM.