So much info was thrown around that it's hard to tell what's been said and what hasn't. I've been in the same boat that you are in trying to find an optic that I liked. I'm not rich, but I suppose that I have a bigger budget than some and often more money than sense. I've tried a lot of stuff over the past 20 years. Please understand that I am not a soldier, nor law enforcement officer. I am a range jockey that used to shoot matches (kids came along) and enjoy an occasional hunting trip.
The TA01 was the first ACOG that I ever owned and after having owned it, I didn't own another for a long time because it turned me off so badly. The eye relief is really short and for me it was uncomfortable. It made it difficult to get into position for some of the awkward shots and getting the right cheek weld was sometimes difficult for me. Also keep in mind that the ACOGs are combat optics meant for shooting at man sized targets. You can do some semi precision shooting with one, but that is not its forte. If you have your heart set on a 4X, check out, I believe, the TA11 (it's hard to keep up with all of the models). I think that's the one with the more forgiving eye relief. In any case, you should do some research on the actual attributes of the different models, because you can't go by the specs on the Trijicon website. The published specs are based on the internal specs of the scopes and NOT actual use. Since you want magnification, you should also check out the TA33. I just got one. It's only a 3X, but geez, it's nice. The eye relief is super forgiving and the horseshoe reticle is really fast up close and there is a BDC as well. It is also pretty darned small and light.
As for the Accupoint, it is definitely more versatile than the ACOGs. The ACOGs were designed with a purpose in mind. The Accupoints were designed to cover a wider range of uses. It's like a conventional scope with the cool lit reticle and good glass. There was some debate over whether the price difference between the TR21 and the TR24 is justified. Believe me, the difference is more than just .25X magnification. The TR21 does beat the TR24 in terms of weight as the TR21 is lighter, but not by much. The TR21 has a bigger exit pupil, but anything over around 5mm is wasted anyway, because that will be more light than your eye can use.
What makes the price difference worth it to me is the eye relief. An AR is one of those rifles where you should develop a cheek weld and then you do best when you stick to it for consistency (nose to charging handle is popular and works well). With the TR21 (and Leupolds that I've tried), the eye relief changes as you go through the magnification range. This may not sound like a big deal, but imagine scanning through your scope for a target. You find it, you reach up and twist the mag ring and then have to change your cheek weld because the eye relief changed. It bugged the heck out of me. On the TR24, the eye relief is constant. Believe me, I much prefer the form factor of the TR21, but I like the TR24 for the reasons I stated. If the eye relief thing won't bother you, go for it. You can make a good deal on a TR21.
On a last note, the ACOGs are really cool. I mean really cool. Just make sure that you look around for one that will fit your needs. Have you noticed how many TA01s are up for sale? Right now, I'm in the position of having to decide whether or not to keep my TA33 because I'd like something a bit more flexible. I just got it a couple of weeks ago and am seeing its limitations in terms of the kind of shooting that I like to do sometimes. I'm looking at a Nightforce NXS. Hey, if you have the money for a T01, maybe you should check out an NXS too. A 2.5-10X24 can be had for around $1200. I've never messed with one before, but everyone says it's nice.
I also have to make a few comments about reticle colors. Although red seems popular, try to check them out for yourself. The color that works the best seems to vary from person to person. For my eyes, red is too bright outdoors (it's common to have to cover the fiber optic on models equipped with it to keep the reticle from blooming) and absolutely useless indoors. When checking out a TA44S with red reticle under bright lighting in the shop, I actually lost the reticle when I ran it across a rack of camo jump suits. Amber shows up really well outdoors without any blooming problems and works well indoors, but I've had somewhat of a problem when shooting from a dark area into a well lit area. In most cases, the reticle just turns black, but in some cases the reticle is really hard to see. For me, green works best. I haven't been able to find any situation where I couldn't see the reticle, indoors or out.