In a word.........NO, well...., unless you have good technique. I used to ride flatland on a Hoffman EP, and found that was all it was good for, Im 5'11" and I struggled to even get it onto a bench, I found it was way too short for anything apart from flatland.
you probably could, but the top tubes on most flatland bikes are between 18 and 19 inches, whereas the top tubes on most street-oriented bikes are between 19.75 and 21 inches. the top tube is where most of your leverage is going to come from for jumping and manuals and other tricks. so a longer top tube SHOULD equal more leverage, unless you're too small to get your weight in the right place, 5'11" isn't too small at all for a 20.5" frame. that's a good size for just about anybody as it's manuverable and long enough to give you good leverage.
i'm pretty sure that nowadays most serious "freestyle" bikes (flatland, vert, street) have 14.25-14.75 inch chainstays. mine has a 14.25" chainstay and a 20.65" top tube. i thought about getting a bike with a 20" top tube for a while because i figured i'd be able to toss it around a lot easier and suck it up under me for bunnyhops and icepicks and manuals and stuff, but i won't know until i try out a frame with my parts set up, and i'm not sure if i want to drop $250 on a new frame if it's not going to work out for me. i'd say the best plan is to go out and ask to try out your friends' bikes and ask what the measurements are on them, if they don't know, then bring a small tape measure with you, or look it up online later at the company's website.
right now i have a terrible one barcode and the frames i'm looking at are the standard lengthy, the mutiny punisher, or the dirt brothers patriot just because i like the star cutout on on the chainstay gusset. but i'll probably just end up keeping the barcode.
Orbea Enol roadie, Fly Micromachine BMX, Fort Track fixed
Flatland bikes are not good for street riding, generally. As Sloth said flat bikes are usually very short (but he's wrong about rear end length, most are around 13.25-14.75), you'll find it hard to get enough leverage. But also, flat bikes don't need to take nearly as much punishment as street bikes and as such aren't nearly as strong. So if you try riding street with something like a Quamen or an Ares, don't be surprised if it breaks, even the longer ones.
If you want to ride a bit of street but mostly flat, I'd suggest either a Volume Mid or a Standard Tao, they're both really strong but have flat-oriented geometery. If you'll be riding street more, just go for any decent street frame with a top tube of around 20 inches, maybe a bit less. A short back end is a good asset for either though.
remember when standard was cool and actually made bikes that people wanted? (like the lengthy and the shorty?) seriously, the "bullitt?" second worst idea ever. the "cashius?" third worst idea ever. getting ride of the lengthy and shorty = worst idea ever. (can you tell i like the lengthy?)
granted, the STA OX is pretty covetted by a lot of kids, but standard is losing ground to smaller companies, i think.