Musical audio synthesis often requires systems-level knowledge and uniquely analytical approaches to music making, thus a number of machine learning systems have been proposed to replace traditional parameter spaces with more intuitive control spaces based on spatial arrangement of sonic qualities. Some prior evaluations of simplified control spaces have shown increased user efficacy via quantitative metrics in sound design tasks, and some indicate that simplification may lower barriers to entry to synthesis. However, the level and nature of the appeal of simplified interfaces to synthesists merits investigation, particularly in relation to the type of task, prior expertise, and aesthetic values. Toward addressing these unknowns, this work investigates user experience in a sample of 20 musicians with varying degrees of synthesis expertise, and uses a one-week, at-home, multi-task evaluation of a novel instrument presenting a simplified mode of control alongside the full parameter space.We find that our participants generally give primacy to parameter space and seek understanding of parameter-sound relationships, yet most do report finding some creative utility in timbre-space control for discovery of sounds, timbral transposition, and expressive modulations of parameters. Although we find some articulations of particular aesthetic values, relationships to user experience remain difficult to characterize generally.