What are the consequences of different clock speeds on different boards?
As was mentioned earlier about the DotStar LED strip/led

There is one thing missing in the calculation above. The End Frame shows as a 32 bit frame of all 1's. That is almost correct. The least obvious is that you need to add 1/2 of a bit for each led in the strip. This is due to the way that the clock is sent down the line. So the 180 led strip would require 90 bits in the End Frame. If you don't do this you will have some of the leds at the end that are not reacting correctly. I know this sounds strange, had me for a while (I use Raspberry Pi).

Also, I have seen where some have tested the SPI mode of sending the data down the line and managed to achieve about 16Mhz clock speeds. Great for POV display.

The DotStar don't require refreshment at all. Each LED has it's own PWM chip built in. They are more expensive than the Neopixel, so it depends on the application as to which is better for you. I loaded my string with colors and then disconnected the data lines (led strip on different power supply) and turned off my Pi. Yup, the DotStars stay as they are.

It has been said they are 'addressable' which is not truly accurate. When sending data, it is the first one, then the second and on. If you wanted, you can change only the first few. Odd hack. Just send the Start Frame (32 or more 0's) and start sending data to the first without affecting the rest of the strip. Note: you might have to account for the 1/2 bit clock loss. eg: 1 bit per 2 leds.

Here is a pretty good description of the DotStar functionality :
https://cpldcpu.com/2014/11/30/understanding-the-apa102-superled/

Here is a Youtube tutorial (2 short videos) that helped me quite a bit:
https://www.youtube.com/playlist?list=PLhXSL6B3uLd551fEQlQGd3LrhzvudKfJQ