I think it was already mentioned but your best bet is to buy a combination of DR software and hardware together so you take advantage of the discount. A new user doesn't need the speed editor on Day One but as you mentioned, one day you will...
To echo what everyone else has said, Da Vinci Resolve is on of the best values out there for what it does. If you buy many of the Black Magic accessories or cameras, you get it for free, like their speed editor or Black Magic 6k cinema camera so...
Yes it's understandable but frustrating that DVR free won't do 10 bit. But DaVinci Resolve full version is actually priced very reasonably, and in a world increasingly heading in the direction of subs-only it remains rare that they are not doing...