I feel there is no advantages and disadvantages. See: Trevor Meyer

highlander is right, its mostly about getting the right frame, parts and setup right for yourself/ particular style of riding. don't follow trends- straight down-tube frames, super high bars 2 pc bars, ultra light or super heavy frame...etc.
that said, with the exception of st. martin and a few Japanese brands, short frames (18.2" t.t and shorter) seem to be on the wane.
 i find frames with steeper seat tube angle (more than 71deg) helpful.

1. http://www.global-flat.com/mobile/shownews.php?ID=4272

2. I just started riding a couple of months ago.  I came in hoping to get a flat specific bike for $300 too.  Was bummed to find out the Opsis was dead because I thought I had it solved in like 30 mins.  Weeks later  I managed $400, but that took some work.  I didn't give up and managed to get another bike for less, but it needed work and I was able to sell the first local.  Dumb luck all around.  The bikes cost a lot for good reason as it turns out.  Between that and that this sport is so damned difficult (so far, also fun) it's easy to see why bikes are scarce.  Where are you?  There's a KGB complete in CO and a Fly something or other in VA on CL right now for $200 that would do the job.  Staring down $650 for an Ares plus shipping and putting it together only to find out you don't dig it might be worth a drive.

Im 5,4 too man ive rode between 18:25 & 18:75 tt's and much perfer the 18:75 ull find being a short arse like myself 2pc bars just dont work for trying to get the leg over youl benafit from a slightly higher saddle so ur not as strech when u grab onto it, this is all personal experience from being 5 foot f*ck all mate

I appreciate all the advice guys. It’s really helpful hearing about other people’s experience especially when they are “5 foot f*cks” like myself. Since I can’t seem to find any decent bikes for less than $650 I’m thinking about just saving up to buy the Ares APLUS. The top tube is 18.5" so that should be short enough for me. Everything else looks good too but I’m curious about the weight. This bike weighs 26lb. Not sure if that includes the weight of the pegs but that probably doesn't matter. What are your preferences when it comes to weight?

Yea it’s gonna take a little while for me to save up for this bike but I’m willing to buy it if it does the job and I can’t find anything cheaper. Here’s the specs:

http://flatlandfuel.com/ares2013apluscompletebike.aspx

see: Japan.

This x1,000,000