So I have a different point of view from what others have said here and I want to preface this by saying that I have by no means any scientifically conducted research based evidence to back up what i'm going to say. Its all going to be anecdotal evidence.
I am not a fan of T2T on very high performance rockets and think that the place where T2T really shines is moderate performing rockets that you want to be able to launch over and over again. If you want your rocket to be a tank that can slam against playa and concrete without batting an eye, by all means t2t.
The issue I have with t2t composited on high performance rockets (altitude records) is: Most of these are only launched one time and the t2t layup needs to be perfect.
@watheyak 's L record has great photos of what shockwaves at mach 3.5 will do. Also, if your composite work is subpar you may see delamination at high speeds which will cause an increase in drag which may cause a structural failure on its own at high speeds.
If you can do composite layups perfectly or you want to work towards that then by all means become a composite master! t2t looks amazing and if you are really good at it then its a great way to turn your rocket into a tank.
This rocket from jurvetsons youtube channel went to about Mach 5, experienced a shred due to the nosecone collapsing in on itself. This rocket shredded at mach 5 and the fins survived. I want to say that this rocket did not have t2t and it was just a big fillet of a strong epoxy. I could definitely see the argument that they may have a short strip of carbon reinforcing the roots between fins but its kind of hard to see in this photo. Either way, its a far cry from going full t2t.
Heres the video and some photos:
*Note: they used a carbon fiber fin can ontop of the aluminum motor tube which may make it appear to be t2t but I do not think that it actually is. Looks like a large fillet of epoxy that has been sanded smooth to me.
Actually in this photo I think it is pretty clear that there isnt t2t since you can see the thick white epoxy fillets
Here is the recovered rocket with the fins still attached!