It's hard to say what the risk really is, or how exactly Amex marketing justifies throwing high value bonuses at people over and over. I have had 3 Biz Platinum cards open at one time, all from the special NLL offers sent to me directly. And more keep coming, but I'm not at a point where I can put large spending on it organically, so will hold off.

My suggestion would be a) strike it while it's hot, you never know when the gravy train will come to a stop, and b) use up the MR points, the value of the rewards of any kind has nowhere to go but down in the long term.

I have been burning my stash down by utilizing the 35% points rebate on the selected airline. That makes each point worth about 1.5 cents. It's not fantastic value, but it's reliable and is as good as cash to me, without pushing to artificially spend more money for an "aspirational" redemption. If you are planning for a specific sweet spot redemption on a particular transfer partner, I suggest you book soon, as lately there have been many short notice and no notice devaluations. If you don't have a plan at all for your "substantial cache", well, get one .