Erik,
Thank you for posting this, but let me take a second to explain how I do things in Miami. Assuming we're landing east (on the 8's and 9) then if you're coming from any direction but due west, you'll be descended to 4k or 6k and given the visual approach on the downwind for 9 or 8r.
This is well within the limits of your aircraft, and you may notice that even in real life, most commercial jets are on the speed brakes all the way down. They maybe not fully extended, but they're definitely out.
If you're coming from the due west, or south west, you'll usually see me give you a 45 or 50 degree intercept for 5 to 7 miles from the airport, and usually this is no more than 5,000 feet. Usually, I give the pilot the visual about 15 miles from the airport, they report it in sight, and then clear you for the approach. It is your job to line yourself up and be descending for the airport. You can either hold off till the last minute and descend, or begin descending immediately to the MEA/MVA/MSA, whichever appropriate, and then land.
Why do I give visual approaches? They're easier, I don't have to vector you all over the place to get you to the airport, I leave that up to you. If you want more room, you can have it, usually. If you wanted to make a short approach, you can do so.
If you're on the ILS, it can take 15 to 20 minutes extra to get lined up. And I assure you, I give you more than a reasonable amount of room to descend. Even by shorthand, if you're 15 miles from the airport, assuming you're in a beeline to it, you can descend from 8-10,000 no problem. And if you need too, you can extend your downwind or make S turns to do so further.
I hope this helps you understand this concept better.
-Tom Flanary
ZMA TA