It depends. Cast iron block and heads don't expand much when heated, so lash shrinks with heat as pushrods (for one) grow. With aluminum heads, the head expands more than the pushrod grows, lifting the rocker assy higher and the lash increase. At least that's the way I understand it.
Here's a link:
http://69.20.53.62/faq_mlifter.php
I like setting lash cold as I can do it consistently (consistently wrong, it appears). With hot lash, the engine is a lot cooler by the time I get to the last few valves, so I"m sure lash adjustments are not consistent.
Best thing would be to set one set when hot, wait till everything is cold, then re-measure and set all others to that measurement.