RE: Should I cancel?
If you plan to Re-order:
Personally, I would just go ahead and get the car now. But I am also impatient, and have already been waiting for 3 years. Otherwise you may be waiting until late summer for your new spring order to be built. Besides, going through the whole process again would be utter agony.
If you plan to buy from dealer stock:
Who knows what the market will be like in Spring. Yes, there may be more cars on the dealer lots, but it may be hard finding exactly what you want for the right price. The SRT8 Spring Special and R/T Classic edition Challengers should be ramping up then as well. If they are, then the price gouging may have abated a bit on the standard R/T models sitting on the lot.
That being said, it all comes down to what is best for your situation. If you dont mind waiting and possibly not getting the exact options you want, then I say more power to you. It would be the more responsible way to go IMHO. You can save your money in the meantime and put a bigger down payment on your car when you are ready to purchase. If you are particular about options and have the "got-to-have-it-now" bug (like me), then keep your current order, or risk even more delays.