Im surprised to see that the AI is thousands more than a side folding TRG-42! You have owned both, at the same time? I agree having 2 rifles is better than one multi caliber, I doubt anyone would disagree. Now realizing I have handled and shot the DTA (Shot Shoot 2013) and in the past I have handled and shot a Sako in 7.62 I have a tough time justifying thousands of dollars more. But then again, I have never ever SEEN an AI much less handled or shot one. You seem to have the most experience in this category than anyone else im aware of? The Mrs. is on board for the DTA or TRG-42 no side folder ($2K price difference!) or the MRAD (Same price as a TRG-42 side folder, but with the Barrett name a more comfortable pill to swallow). I doubt I could convince her of the AI being "that" much better! =)
I wouldn't say I have the most experience or even close to it, but I have experienced all of those platforms and have a good bit of use behind them. Most of my 338 shooting was with the TRG and the AWSM. I didn't own them both at the same time but I did shoot an AWSM while I had my TRG which is what made me switch.
They are both top notch guns but the AI just stands out for me. They both have an excellent 2 stage trigger, an ergonomic stock, 60 degree bolt throw, slick actions, and just all around excellent quality. The first and foremost reason I switch was because I liked the way the AI shot more. It recoils less (weighs slightly more too), I prefer the ergonomics of the AI stock, and the barrel held its accuracy longer for more shots. My TRG opened up a little after 3 shots, still well under MOA, but it didn't hold it's accuracy like the AI does.
The AI only has one possible downside to the TRG, and that's weight. Not a bad thing in my book though and its not like its 5lbs heavier. The next is the cost of acc's for the TRG. It seems like everything is $300-500 for it. The mount is $500, the bipod is $600, the spare mags are $400 (for one fucking magazine!), the brake is $300. So assuming you buy their stuff you're looking at an extra $3k for parts (I like to have at least 5 mags total). That is on top of the $4000 you're going to spend on the TRG with the KRG folder upgrade.
Two more reasons I strayed away from the Sako is support and the stock. A buddy of mine dropped his TRG22 and cracked the stock right at the grip (shouldn't be an issue with the KRG) so its definitely nowhere near as robust as the AI's chassis. Sako was a nightmare to deal with and took months to complete the warranty service. We both live within about 30 miles of both Sako USA and AINA so we can drop anything off if need be. 3 months for a simple stock replacement was ridiculous and they offered no loaner rifle of any sort. I've heard of similar stories from others regarding their service. Shit can go wrong so it's just something to think about.
AI on the other hand warranties two mags for me in person within 10 minutes of walking through their door. My guess a repair on a rifle would have been no different as long as they had the part, or had the same rifle sitting there they could take it from.
Just a couple things to think about. Especially the extras you'll need and the prices Sako charges, their are aftermarket options for a lot of them (some not really any cheaper) but as far as I know you're stuck paying their prices for the mags. AI mags will run you about $80-90 each, their mounts are $180, the bipod is $200 or the plug and play atlas is $270, and the brake is included with the rifle.
I would suggest giving Mile High a call and see what they can do for you. They also have a good deal going for a couple demo AX units with less than 200 rounds for $6850 with a $450 spuhr mount.