However, since this is final output and I don't need to modify these in any major way, I am starting to make HQ Jpegs. I am not too much concerned about loss of non-visible info as I dont need that.
What will you be using the final product HQ JPEGs for? Viewing on screen, printing?
Don't forget that conversion to an output profile is also a major number crunching operation, and it would be a shame if the carefully converted HQ JPEG falls apart at the final step. Also, converting to a smaller gamut colorspace comes with trade-offs, best postponed till late in the process.
Looks like Adobe RGB will be the way to go for this. Although some people say that you gain more gamut in Adobe at the cost of luminance. Anybody know if it is true or of consequence?
Well, Adobe RGB seems to be a better choice than sRGB, and I don't think Luminance suffers in any meaningful way. sRGB does record the shadows a bit different, due to the shape of the gamma curve used, but again it depends on your use of the files whether that matters.
If you are seeking a replacement for your 16-bit/ch TIFFs, maybe a more flexible compromise would be HQ JPEGs in the BetaRGB
working space. That would still allow to do significant colorspace conversions with little risk, and you can use a high quality JPEG compression (without chroma sub-sampling) to preserve almost all color nuances in your 16-b/ch TIFFs, as far as output is concerned.