I have NEVER been a fan of combo modems, even when back there WAS a significant amount of $$ to be saved by choosing one.
Since I switched from DSL to Cogeco (and eventually to START), I received (by luck or by not asking "What else have you for modems ?") a DPC3000 unit from Cogeco, and as such asked for and received another of same from START.
Therefive, on install day, I was able to simply substitute the DPC3000 for my old DSL standalone modem, change my router to a DHCP login instead of PPPoE, and I gained an Uncle BOB.
Any pre-existing pros & cons of my router were unchanged, and almost ZLC
(Zero Learning Curve).
I was about to offer the identical advice as in Marcer's comment (1) and closing comment, and I suggest that doing so would be your best advice at this time, unless Cogeco approves any further D3 non-combo modems by the time you call them.--
We have only 2 things about which to worry :
(1) That things may never get back to normal
(2) That they already HAVE !