I run a Rolleicord IVB, my favorite camera; It's comfortable and a wonderful lens. I use a C33, but it needs a tripod. I have been using a Voightlander Bessa I, which is wonderful to travel with. My system camera is a Mamiya Universal with a 65, 127 and a 100. Sold a 250 F8 because it was hazy. Ultimately I like to shoot full frame and I love 6x9. I had a guy ask me last week (who was using his whiz bang new Nikon DSLR) about my Bessa. He asked "what lens, blah, blah". When you shoot 6x9 most optics from the majors are all good enough. Shade the lens and fire away! Snobs worry about brand names. Blads are great, don't fit my hand the way I expect a camera should; I would take one, but wouldn't buy one until they're cheaper. That's personal. Some people like the little notch on their neg and print all of their Blad images full frame so you know what he's using. If I am going to carry a hunk of metal, I want the biggest neg in return.
If your happy and you know it, keep the Pentax. It's cool you can use the Blad for awhile because you may find it works better for you.
My dad was an amatuer photographer when I was a kid. Shot a Graflex XL and later a Mamiya 645. Just the other day he was asking me about DSLR's and how he read lenses more than a couple years old are no good. My best lenses are at least 30 years old.
What I learned about photography from RIT that always sticks with me is this "It aint about accuracy, it's more about consistancy". Perfect camera holding, processing, exposure, composition etc. makes a much greater impact on image quality than the optic. The optic, unless it's been dropped or something, contributes about 1% to the overall quality of a finished print. All of you you do your own processing KNOW I am speaking the truth!