Robotics software systems have a large and domain-specific range of quality requirements that make development of reusable software a particular challenge. Frameworks and middleware have a major impact in this respect - on both quality characteristics and development effort. As framework design involves many tradeoffs, they have different quality and feature profiles - with no existing solution clearly superior. Analyzing existing approaches, the principle of customizable quality tradeoffs is identified. The proposed design approach aims at maximizing the principles of concern separation and customizable quality tradeoffs in frameworks: basically decomposing them into one ( optional) module per concern. This allows localizing quality requirements and flexibly tailoring frameworks to application requirements. In particular, all operating-system- independent concerns can be run "bare metal". The proposed concept was implemented in the FINROC framework. The benefits on quality characteristics are evaluated in a case study. The framework is run "bare metal" on an FPGA soft core - notably a platform not originally targeted.