Buy the Breville BHM800SIL Handy Mixer.

It is built for people who actually bake, not just people who own a mixer.

What was compared

1. Precise control from meringue to heavy dough
Breville's 9 speeds plus boost let you dial in exact power for delicate whipping or thick batter. The Black+Decker's 5 speeds jump so hard that owners report batter splattering out of the bowl past speed 2 or 3.
2. Scraper beaters end constant bowl-scraping
The Breville's scraper beaters wipe the bowl sides as they mix, and one review estimates that saves roughly 7 minutes per session, about 9 hours over three years of regular baking. The MX600T's helix beaters just spin, leaving you to stop and scrape by hand.
3. Beaters stay locked in, not falling out
Black+Decker owners report the beaters come out way too easily mid-mix without pressing eject, a real hazard with hot batter or a running motor. Breville's BeaterIQ release is designed to only let go when you tell it to.
4. Rated the real top pick, not just the cheap one
Independent hand mixer roundups name the Breville their winning pick outright, while the Black+Decker lands as best budget, a tier below on the same tests. That is a gap in sustained performance, not just packaging.
5. Yes it costs $100 more. Worth it if you bake often.
At $159.95 against $59.99 the Breville is nearly three times the price, no getting around that. If you mix more than a few times a month the scraper beaters and finer speeds earn that back in saved time and fewer ruined batches; if you bake twice a year, keep your cash and grab the Black+Decker instead.