Your return on investment on a Masters CS degree will come over time.
For example, once you finish the degree, you should be in a better negotiating position in your current company when discussing promotions as you have demonstrated a willingness to follow through with personal development in service of the company.
If you lose your current job, having a CS degree is great future risk mitigation. While a portfolio and experience sounds good enough, you'd have to jump more hoops through HR without a CS degree. But once you have it you could get a job almost anywhere you want.
>FWIW, 'patio11 has some high quality experience with the engineering hiring market and has written some seminal texts about it.
This is important to know. However, I think it would be better of patio11 to open his comment by stating a short summary of this experience in order to lend more credence to his suggestions.
>there may be soft skills that you may not have yet and may never acquire
I'm curious about this. Especially on the "may never acquire" part. You mean that there are some soft skills that some people would never attain? That's interesting to me and I'd like to know why.