+1 on what Stoox says here. Unfortunately, our market has been confused with this type of marketing. There are other reasons some scopes look "brighter" in lower light than others that actually have nothing to do with coatings or so-called "HT glass". In fact the human eye is a very poor comparative detector to brightness change. Furthermore the light transmission numbers being marketed as 96% and such are not entirely accurate. During a discussion with an optical engineer a while back I found that it's actually impossible for a scope with that many lens elements to achieve 96% light transmission... true light transmission, because light is absorbed by glass and these companies are simply not counting the "light absorption" through each lens. They are only accounting for the loss due to reflection at each surface. Absorption is actually a much greater contributor to light loss, this can easily be proved in a lab with a photo-spectrometer.
So what do I mean by "reflection", let's take one of Schmidt & Bender's Ultra Bright scopes with a claimed light transmission rating of 96%, how did they come to this number? In this case it is a math equation, they take each lens element in the scope and determine the reflectivity off each surface - the front of the element and the rear of the element. Now it's just simple math - let's just say the scope has 10 glass elements inside it, in a perfect world each glass element would pass 100% of the light but since we don't live in a perfect world as light passes through each element it looses some "brightness". So if a multi-coated surface is claimed to be 99.8% that means you loose .2% for every surface, in our example we have 10 glass elements with 2 surfaces each, so .2 x 20 = 4 or 4% light loss in this case and 100 - 4 = 96% which becomes the number the manufacturer uses, but as was mentioned above, what the manufacturer is not taking into account is the amount of absorption that occurs in each glass element.
That is not to say that the Ultra Brights and other scopes marketed with "high transmission" don't perform well. I have been on the hunt for light weight low light optics for years now and have been surprised to find that some I thought would perform well did not and others I did not think would actually did, this includes some scopes with smaller objectives vs. other scopes with larger objectives. While the laws of physics apply and generally a larger exit pupil means more light will reach your eye, other factors in the design of the scope may contribute to one scope "appearing" brighter to your eye than another.
OP, from personal experience I can say the Premier LT (of which the TT315M inherited the design and then improved upon it in certain areas) is a phenomenal low light scope; however, you did not mention if you are looking for SFP or FFP. Almost all my rigs are designed to be field used (hunting) first and then long range second so my first priority is usually weight and while years ago I was a huge SFP advocate who thought BDC reticles were the end all be all, I've "come to the light" as it were and now all my rigs have FFP scopes on them (well except for some of my AR-15's, but they are the exception and not the rule). What I mean to say by that is that if you are convinced that SFP is the way to go for hunting then I understand, I've been there, but I would ask you to seriously consider the pros and cons.
Finally, I would highly recommend you look at ILya's (Koshkin) advice above, he knows his stuff and I don't think I've ever seen him give bad advice.