I have the .50 HTI. It's a nice rifle and I got it before the prices on them went way up. It's a simple design and it's short and light. The single stage trigger isn't just good for a bullpup, it's good for a single stage, period. Maybe one of the best factory single stages? When I got it, I got it with the idea I'd maybe get the .375CT conversion down the road. But it's expensive, expensive enough to just put in another rifle. And I decided to get a .338LM anyway.
So for a dedicated .50, I kinda wish I'd gone with the AI for a number of reasons. It's heavier and longer, but as a rifle in a dedicated caliber, I think the AI would have been a better rifle. There are a couple of other repeaters I think would have been nice too like the McMillan. These are heavier rifles built for heavier use IMO.
But for weight and size, and for a good rifle in general, the DTA rifles are almost impossible to beat. Especially if you are into changing calibers. It's not a bad rifle despite the negatives I mention.
Not sure about the SRS, but on the HTI the difference in length on the mags is made up by an extension. .50 doesn't have it, but the CT's do. If SRS has .338LM length extensions (the largest caliber SRS accepts) on the smaller .308, etc. mags, I'd get something else were it me. The mags are "okay" but cost a lot for what you get. They sell barrel extensions so you can have barrels cut elsewhere, which is a plus.
For the .338LM I looked at AI rifles and they're nice, but since I'm not gonna do caliber changes and a quality, dedicated traditional setup weighed like 11lbs. less, I decided I'd get a McMillan .338 when I can. I already have an Elite Iron can for it, so that's heavy enough to lug around. If I were gonna get a bolt gun in 6.5 or so, I'd probably either have one built or go with one of the GAP rifles; if I wanted a chassis, it'd be an AI hands down.
I know these aren't the calibers you were considering, but the platform is similar. DTA is a good, simple, compact and lightweight multi-caliber rifle, but it lacks quality of build (due to it's simplicity, a plus but also a minus) and durability. It's not shoddy work at all, it's just simple, so don't get me wrong. I understand the SRS doesn't fare well at the Steel Safari and it's not a rifle you'd wanna deploy with I hear. The .50 may fare different, may be much tougher than the SRS, I don't know. It is a solid rifle and with .50 at least, the mags are normal, no weird extensions. For the price I paid, it was impossible to beat. For the price they charge now, I'm not sure. It fits a niche is the best I can really say.
For a full length top rail on a long range rifle, particularly the HTI, you'd think it'd have a rail with at least 20MOA, but no, they're all 0MOA. It'd be nice to have built in MOA for night vision or as an option just in general.
As for your smaller AI, keep it, it's a good rifle and you won't be gaining anything but a shorter and possibly lighter rifle with the DTA, and the ability to convert to other calibers easily. If I really needed it that short, I'd probably be opting for the Covert too, which has even more pros and cons but basically has no competition I'm aware of; I'd probably get that in 6.5Grendel due to length unless another outperformed it. If you really need that, I suppose it could be justified, say for very long hunting trips or hiking for days or for badass boltgun setups that'll fit in brief cases. I'd consider it for that, but otherwise if I were to get a 6.5 today, the DTA wouldn't be in my top 5, however, some variant of your rifle likely would be.
As for accuracy, they are mostly barrel, ammo and shooter dependent; have a good barrel, ammo and shooter and they'll shoot as good as any.