Which home providers for OWL?

So far, I have only seen the construction service descriptions from Kelle and the red Splietker. In my view, they do not differ much. With Kelle, I had the impression that he likes to build KFW55. In the basement with underfloor heating. Red Splietker prefers KFW40+, but with climate doors in the basement hallway, so the room is probably separated. (At least that's how I understood it)

DF bricks were not on our radar at all.

... and why (and on whose advice) was it done after all?

We recently also visited the blue Splietker and I can only agree with the words here. We also had a very good conversation there. In the end, I inquired about the two companies. Due to conflicts, a mason separated and apparently co-founded the other company and is now the namesake. For us, the whole thing has a bitter aftertaste, because a house we liked was built by Splietker (blue). However, the pictures of it were also displayed by the Red one and we were never corrected in our assumption that the house was not planned and built by that company. It is probably true that the mason worked on it and had the right to take the pictures over. Hence, a certain bitter aftertaste, especially regarding the red Splietker. Looking at the costs, the Blue one is, as already described here, quite a bit more expensive. We have not yet received a "proper" cost estimate in list form from Kelle, but so far only oral statements about how much a house might cost.

Due to conflicts, there was a separation from a bricklayer, who apparently then co-founded the other company and is now the name giver. For us, the whole thing has a bad aftertaste, because a house that we liked was built by Splietker (blue).

Yes yes, rumor has it that the similarity between the Peugeot RCZ and Audi TT was also explained to me by the change of employer of a designer. Whether and how the similarly named companies are related by marriage, and if so in which succession, seems to me of secondary relevance. Hans and Friedrich Grohe both make quite decent showers, period. Both Splietkers seem to me to be worthwhile construction companies, even if one were polka-dotted and the other checked instead of blue and red.

We have now caught up with our general contractor regarding the superficial cost disadvantage at Splietker.

May I ask which general contractor you are building with in OWL?

I can reveal that once we are done and have gathered all experiences from start to finish. :)