A great starter street/track boot are the A* s-mx boots.
Blunt honesty: There are better boots. There are far worse boots. There are plenty of riders who have been down at high speeds where this boot has served them well. There are riders who went down at slow speeds where their ankle still twisted up.
My opinion: This boot is great slide protection and 80/20 overall protection. If you feel your ankle may be "crushed" or "twisted up" during a down, then look at something with more ankle restraint.
What I personally wear.
Pros: 95% adequate protection. extra slide and heel protection
Cons: Sucks to walk in of a long period of time, lack of ankle crush/twist protection
Price difference between those two boots, about $100 dollars.