Mostly, yes. Technically speaking, if you had EVERYTHING on the SSD and NO spinning drive, the machine would be faster than having the OS and some applications on the SSD, and the rest on the spinning drive. It's not likely to be noticeable, however. Most of the noticeable speed differences, as the above poster pointed out, comes from seek times, not necessarily read/write speeds. So, if you didn't have enough room on, say, a 128GB SSD and installed an application on the spinning disk, that application could potentially feel 'slow'.
So, in THAT case, the 512GB SSD would be faster. There are also two other advantages to running the 512GB SSD instead of a small SSD / Spinning drive combo. For one, battery life. Though not significant, running an SSD+Spinning Drive combo will use more battery than JUST an SSD. If you swapped your hard drive out for an SSD and did not install a spinning drive at all, there would be a slight bump in battery life. If you installed a spinning drive AND an SSD, there would be a slight drop in battery life compared to what you have now.
Secondly, is noise. A spinning drive is one of the noisiest components on a MacBook Pro. Running just a solid state drive will make the machine ultra-quiet in low end tasks, when the fan doesn't have to spin up (web browsing, e-mail, etc.)
Bottom line, 99% of the time an SSD+HDD combo is generally going to be much, much quicker. Unless you are doing a ton of file intensive tasks, or running a huge database, you aren't likely to notice. If you're storing photos, music, movies, etc. on the HDD and Software and the OS on the SSD, I really think you'd have it perfect. Try and get an SSD big enough to store ALL of your applications, plus the OS. Then leave your HDD for music, movies, downloads, documents, etc.
One option would be to put your optical drive into an enclosure.
Optical Drive enclosure; $37.99
http://eshop.macsales.com/item/OWC/VLSS9TOPTU2/
OWC Data Doubler; $44.99
http://eshop.macsales.com/item/OWC/DDAMBS0GB/
Crucial M4 128GB SSD; $110.99
http://www.newegg.com/Product/Product.aspx?Item=20-148-442&ParentOnly=1
TOTAL: $193.97 + Shipping and any taxes
Or, Crucial M4 512GB SSD; $389.99
http://www.newegg.com/Product/Product.aspx?Item=20-148-450&ParentOnly=1
Note that there are cheaper alternatives to the OWC Data Doubler or even the Opti-Bay. I just used those for a baseline, and it's what a lot of us use. It also includes instructions, and all of the special screwdrivers. That may or may not be necessary for you, but for some users less comfortable with cracking open the machine, having everything in one box is valuable.