I don't know where you got the idea that postop vaginas are less like to spread STD and HIV - that is absolutely incorrect, as scottieM posted.
Barebacking is a risky proposition, not only due to the risk of HIV, but there are now multiple drug resistant STD's out there. In the past if one got gonorrhea, syphilis, chlamidya a simple course of antibiotics could take care of the infection. Now it is getting to the point where only one antibiotic may work, and it may soon be none.
Using condoms is the safest practice - and there are some ultrathin condoms that deliver more sensation than the standard ones. I recommend the Okamoto brand. In Thailand the 0.03 size are available in the 7/11's. I haven't seen the 0.02 size yet, but they will probably be available soon. Also remember don't use mineral oil or any oil as a lubricant with latex condoms as they will become degraded and break. Water based lubricants only for latex condoms.
I simply supposed that since the venereal fluids of post-op vaginas are bound to be different to those of the natural female sexual organ then maybe there is less chance of sexual infections being transmitted during sexual intercourse with post-op ladyboys. I certainly didn't think that post-op vaginas were added plastic parts as Scottie's post would suggest. I have watched many videos of the surgical creation of Tgirl pussies. I have seen enough to know better!
To be honest, I am largely ignorant about the ways in which sexual inflections are transmitted. I have never done too much research on the subject because I know that a little knowledge would set off my OCD and affect my performance when I have sex with escorts or other women.
I have always had problems with condoms. Most of the time I cannot ejaculate with them or sometimes they will just kill my boner completely. There have been times when I have gone to see a good-time girl and not been able to sustain a full boner at all upon being forced to wear a condom which seems more like a rubber balloon on my cock. I have had more than one of these experiences of disappointment.
I have thought to myself that maybe I should start using cialis pills before such prostitutory encounters. I am in my 20s, but I often have difficulty achieving a full boner when I am with escorts. This is most likely because of some form of anxiety. Maybe I am sexually awkward in addition to being socially awkward. Using condoms seems to make everything worse.