You need to provide more details, first off. But if the biggest reason for you is because it is cheaper than it's 'new price', it doesn't sound like you need it to me. Btw, how much of a savings are we talking about (absolute and percent)?
Cost in the netherlands for this router is starting at 325 euros including tax, i can get the router for 282 euros including tax
What are your ISP speeds? Are you expecting to be able to increase your ISP speeds substantially (soon)? Speeds are 100 100 through glass fiber speed won't change
How many devices (N Class, AC class, wired) are you currently using on your network? Will this change drastically soon? About 15, will stay the same most n class
How are your current devices being used on your current network? Is the NAS being used 24/7 with multiple clients? Is streaming a high priority for many devices? How many concurrent users with how many concurrent devices are using the network at any one time? Nas is 24-7 also uploading backups to several cloud services. Sometimes streaming video to tv or tablets, this will increase a little
The most important question though is how is your current router handling the network load today? Is it struggling? Is it randomly rebooting, or giving other signs of being overly stressed? Is there a certain feature that you need from a new router that your current one doesn't offer? The 68u is also used for voip, when nas is uploading/synchronising to cloud voip will have lags so the conversation cannot continue. Router is not having any problems from itself
Buying something just because it is on sale is not a reason to buy.
If you have more concrete reasons (not for us, but for yourself) to upgrade from what you have, that is another story. But everything you have presented so far points to 'keep enjoying your current router', to me.
