"But let me ask this question. In principle, if all the chips in a given casino are the property of the casino and I take some of those chips, can I be accused of theft? And in follow up, if some of those chips are roulettes and some are regular chips vs. regular chips only, is the theft any degree greater?"

Jim, in a previous post I posted a portion of the NV theft statute.

To answer your question, I am assuming that when you say you take some of those chips you mean you leave the casino with chips you bought.

In that case since you have a right to possess the chips and you came to possess them lawfully i don't think that this qualifies as a theft.

Now if you are asked to cash in your chips, or if you are aware that the chips (roulettes and tournament chips) are not supposed to leave then I think an arguement could be made that the theft statute applies.

However keep in mind that their may be other laws which also apply, for example statutes relating to cheating. I have not read them I just point out that theft is not the only possible crime here.