Hi Illousian, Wilkommen to The Mattress Underground 
Glad to have you here!
Your English is fine, and I understand your dilemma in finding a new mattress. First, I would suggest, if you have not already done so, that you take a look at our
Mattress Shopping Tutorialto get a feel for what to expect while mattress shopping, as well as the Mattress Specifications You Need To Know to get a better overview of what to look for.
Any mattress is unique to the sleepers using it, based on their stats(height, BMI, sleeping position(s) and any underlying health conditions, and their PPP( Posture and alignment, Pressure relief, and Personal preferences); thanks for providing your stats! You don’t say what type of mattress you are using now, but it sounds like it may be too firm, as you are having shoulder pains on awakening. As far as the issue of you sleeping hot, a mattress topper or cover made of breathable materials like cotton, wool, or coconut coir could relieve this, allowing air circulation between your body and the mattress material; also an elevated base and/or innerspring coil layer would allow air circulation as well.
You may also wish to review this post that addresses the many contributing factors to the microclimate of a mattress.
There are 2 types of latex normally used in mattresses: Dunlop, which is ‘natural’ or ‘organic’ has a more supportive ‘cradling’ feel which you may like as you say you don’t ‘sink in’ to your current mattress. Talalay is considered ‘bouncier’ or ‘springier’. The Wilfried Scholz Silencio is a zoned 7" Dunlop mattress with a zippered quilted Lyocell fleece cover. This is a durable mattress and has both H2 and H3(plush and medium) firmness options. Sorry to hear you had a poor experience in the store…if you tried out the medium comfort level you might prefer the plush, or vise versa. A slatted frame would allow for good air circulation as well
I looked at this bed, and it does appear to be an innovative design, with the wooden slats made with more ‘elasticity’. The Talalay mattress is of a lesser thickness than the Silencio, but the wool cover would again provide good air circulation between the latex and your body so should allow you to sleep ‘cooler’. It is a more expensive bed system, but seems quite durable from its construction.
The Dormabell Innova is a custom system where your shoulder width, waist width, pelvic width, lumbar position and depth, knee position and depth, the preferred sleeping position, weight and height are used to design a bed system specified to you. I agree with you that though this is highly customized as this is made of polyfoam, the mattress could wear prematurely, depending on the chemical composition and density of the foam used. Their promotional materials do appeal due to the ‘science’ – but keep in mind, only you can tell which mattress is ultimately comfortable for you. I would recommend trying out various firmness levels of talalay to see if you can find one that suits you, and not pay too much attention to the ‘marketing’.
As for the polyfoam, you have a lower BMI, and 2.8lb/cuft should not present any issues for you…you can take a look at theMattress Durability Guidelines to see how various materials hold up over time. Ultimately it comes down to what feels best for you; A mattress is an important purchase so its always good to take the time to try out as many as you need to ‘zero in’ on what suits you.
I hope this helps; possibly some of our other German forum members can chime in with their thoughts as well.
-Basilio