here is one that shows stable levels in subcutaneous injections for females to males.
Intramuscular (IM) testosterone is the most common modality for testosterone therapy of both male hypogonadism and female-to-male (FTM) gender transition. However, IM injections can be painful and often are not self-administered by the patient. The ...
www.ncbi.nlm.nih.gov
this study below discusses IM TC vs SCTE. Shows SCTE has lower Hematocrit and e2. SCTE shows the same Testosterone levels too( i thought it would be lower if anything).
I am assuming that since it is slower release, prevents higher peaks and lower troughs.
While IM-TC and SCTE-AI provide a significant increase in TT levels, SCTE-AI is associated with lower levels of post-therapy HCT and E2 compared to IM-TC after adjusting for significant covariates. SCTE-AI is an effective testosterone delivery system with a potentially preferable safety profile...
pubmed.ncbi.nlm.nih.gov
I think some of the other studies conclude that it is more easier to perform and is painless compared to IM for a long period of time. etc