I will support some points already made and add a couple of comments.
I'm still a little unsure if i want a harness with shoulder padding and quick release, or just a pure tek harness.
Shoulder padding - no. Quick release, on one (left) shoulder - well worth considering.
Are different BPs designed to work differently?
Generally no, with the exception of the material (and therefore the weight) of the BP. There may be some product lines with different size plates, but they perform the same function / 'work' the same. The hole spacing is generally going to be 11" OC, or a hole (or several holes) at the top, and a slot at the bottom, to allow use of a STA, or doubles. One point of non-commonality - certain manufacturers market covers for their plates (to allow you to slip a lift bag up under the cover, for example. These covers are often held in place by screws mounted to holes drilled around the periphery of the plate. Not all of these peripheral holes are spaced the same, across manufacturers, however. A minor issue, just mentioning it for completeness.
Do all BPs need STA's for single tank diving?
No.
Is there really a wing out there that is able to do both single and double tanks?
No.
or am i better off just focusing on single tank setup for now and purchasing a new wing later?
Yes.
adamp69:
Ive heard some ppl say that a donut is better than a horseshoe? any truth to that?
Hard to say, for most divers. I have both, and really do not find much of a difference. The trend is toward donuts, but both work just fine, at least for me.
I will stay out of the brand discussion. I have multiple brands of plates and wings, and it is hard to say there is a clear difference in product quality or functionality. I confess, I really like the support you get from DSS, and Tobin. If you have questions about their rigs, or are confused by something on their website, don't let that prevent you from considering them. Just call them up! Helping customers (and potential customers) out by phone and email is part of what they are very good at doing.
spectrum:
I made my harness with shoulder releases and sliders. . . . The LH release is especially nice when dropping my rig while wearing my DS. It totally avoids snagging the vent valve.
Echo this sentiment! While some may be unenthusiastic about having a shoulder quick release (failure point, etc.). I am not one of those. Frankly, getting out of my harness, after a cold water drysuit (and thick undergarment) dive, with doubles, is a pain. Even with a single tank it is. So, I really like being able to unclip the left quick release and get out of the harness.
I have multiple BP harnesses, two of which are commercial, the rest of which I made up myself (some with the help of my local shoe repair shop) from webbing, a buckle and some D-rings and tri-glides. I see no particular advantage to buying a commercial harness, unless it is very inexpensive, or the convenience is worth it to you.
SangP:
You can't cut a hog harness n add a qr unless u have a handy heavy duty sewing machine available.
That's what your local shoe repair shop is for. As others have noted, you can also use some stainless steel tri-glides.