G'day Jaron,
I'm with Peter mate, your images are what's important here and you've posted some excellent work in this thread. Having said that I'd love to see what you could create if you hired a 645Z and 90mm macro too.
As you already have the K-1 I can see you will get a lot out of pixel shift with the types of subjects you shoot, so that new D-FA*50 lens might be one for you to try out as I expect it will be the new pinnacle of sharp for Pentax (an opinion only of course but judging by the latest D-FA* zoom lens I reckon that's a reasonable expectation). Hopefully we'll find out when the D-FA* 50 is coming to market soon.
You've done your lens research so you may be across this already, but just in case you weren't I thought I'd make mention of some less obvious lens choices. You seem cool with manual lenses which should mean you'd be cool with using Zeiss. There are ZK mount options, they are limited to some but not all the Zeiss 'classic series'. There's about 20 on ebay at the moment (only in 25/28/35/50/85). The prices are all over the place but I use ZK lenses so can recommend them, especially the Makro Planar options if you can find them. But looking beyond ZK is really why I mention the Zeiss option as this takes you from nine ZK options, some of which are very rare and hard to find, to thirteen Classic and eleven Milvus options.
The extra options exist through the Leitax mount for the ZF/ZF2 series of Zeiss glass in Nikon mount. The adapter is added to the lens and is reversible should you want to return it to Nikon mount. The adapted lenses work like an M42 lens which is not as flexible as a straight K mount option but is very easy to use on the K-1 and the quality of the lenses means it's worth a mention, IMHO, YMMV etc There's some adapted lens shots in this thread:
Carl Zeiss T* ZK mounts (Distagon, Planar, Makro-Planar) - Page 10 - PentaxForums.com the linked page is where the first Zeiss/K-1 images start with the ZK options.
Now to sound like an ad; 'But that's not all': Leitax adapters can also be used on some Contax Carl Zeiss, Leica and manual Nikon glass, which again opens up a new range of lens options that most people wouldn't consider when thinking shooting Pentax. The Pentax A mount lenses are likely to be cheaper and do all that you want them to do but if any of this sounds interesting you can check out Leitax adapters here:
Nikon and Zeiss ZF lenses for Pentax cameras
It's always good to hear how people get on, so I hope you can share more of your work with us using whatever lenses you go with.
Tas