Hello everyone!

Recently I finished all of my facial related feminization surgeries, and I am satisfied that whatever could be done to feminize my face, has been done and that the doctors did a very good job. I can even sing more easily after my rhinoplasty, which is a nice bonus. I don't think my face looks as feminine as I wish it would, but I think this is as good as it gets and it's pretty good. My face was what I was most dysphoric about.

I have an upcoming SRS + breast augmentation surgery August 2017, and I'm kind of wondering whether or not I should do it.

On the one hand, I am certain that it will give me more confidence in my femininity and help me feel less dysphoric and more confident about myself.

On the other hand, I don't hate what I currently have down there with a passion, like I hated my male facial features... (and even now what's left of those male features)

I want to use the time I have until the surgery to be sure I am not sacrificing anything especially significant to me before I hit the operation table. Specifically I am wondering about long term health outcomes after SRS. I know that for many trans woman it's either suicide or surgery, but for me that is not the case because I do not utterly despise my current genetalia like other trans women might. The doctors keep telling me not to worry, that whatever might happen after SRS they have the tools to deal with...

...but still I am wondering if there are any studies out there demonstrating any effect of SRS on longevity and risk of disease or disability?

I don't think there is any research suggesting that SRS increases mortality or morbidity.  There is some research supporting there is no difference, but it's not super convincing.  There is at least 1 study that shows transsexuals receiving SRS have a greater risk of mortality relative to the general population.  But pre-op transsexuals also have higher mortality, and they didn't compare pre-op to post-op transsexuals, so you can't really learn anything.

One advantage of SRS (or orchi) is that it allows you to reduce estrogen intake and stop anti-androgens.  So if HRT does increase mortality risk, you could imagine SRS might reduce mortality risk.  However, the research I have seen suggests that modern HRT regimens do not affect mortality risk very much, so this effect might be small.

Anecdotally, people report much higher risks of urinary tract infections (UTIs) following SRS.  UTIs can result in septicaemia, which has a pretty bad mortality rate for people aged 65+.  Of course, I have no estimate for the magnitude of this effect and women in general are at greater risk of UTIs.

Here's a brief summary of some articles I've looked at:

Here's a study which did not find higher mortality among people getting SRS.  Mean follow-up was around 15 years for MTF transsexuals.  Like most of the research in this area, they are only comparing pre/post.  There's no control group.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4822482/

The above study does a pretty good literature review on page 2 that is relevant to your question.  However, most of the review is focused on long-term effects of hormone therapy as opposed to surgery.

Here's a study which found that 16% of MTF transsexuals experienced some incontinence following surgery.
http://www.sciencedirect.com/science/article/pii/S0302283804005159

Here's the study that found higher mortality compared with the general population. 
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0016885

Here's a study that did a 6 month follow-up survey on 66 patients receiving surgery.  90%+ were pleased with the aesthetic outcome.  They don't look at mortality or disability, but they do look at complications.  Complications were pretty rare:
Meatal stenosis 7%
Severe wound infection 6%
Rectal lesion 3%
Necrosis of the glans 3%
Vaginal prolapse 2%
Necrosis of the distal urethra 1%
Lesion of the external urethral sphincter 1%
Urethral Fistula 1 %
http://onlinelibrary.wiley.com/doi/10.1046/j.1464-410X.2001.02323.x/full

Here's a study that looked at 232 transsexuals receiving SRS.  The results are really positive, but there is a huge follow-up loss (68%) so response bias is probably an issue.  They don't look at mortality or disability.
http://link.springer.com/article/10.1023/A:1024086814364

Thank you for the information packed response! Really really really thank you!

It's such a relief compared to what happened when I tried to ask in my local country forum, where they pretty much told me that if I wouldn't rather die tomorrow than spend another day with my current genetalia then I shouldn't get SRS done. It's refreshing that I am able to ask a research question and get a research answer.

My main concern is that perhaps there are more functions to the anatomy in that area besides urination and sexual reproductive functions, that maybe it's more than just a testosterone factory, and that perhaps I would be losing some vital function for my long term personal physical health by changing that anatomy that cannot be replaced by hormone replacement therapy...

...or does it seem that it largely has no signifcant effect on this and that I can have a reasonable chance to get a good healthy lifespan like everybody else through nutrition and exercise?