The Sako A1 chassis is great in many ways. Granted that I have limited exposure to it, but I feel that everything you want is there.
I have however shot with a TRG 22 for a few years. While I dont mind the original stock, there is no real adjustability to it, exept the buttpad height. Other than that you need expensive spacers and frankly that sucks. Thats why I switched to the KRG w3 rear folder pretty much from the get go.
The original front section is bulky and a bit fragile too. If you dabble in PRS type shooting, the original pretty much sucks as it is short and have a high center of gravity. So I switched to the Vision aluminium front and its awesome. Expensive, but still awesome.
So, while the A1 chassis is not a PRS chassis, and PRS is not the benchmark to compare anything and everything too. It has all the adjustments you could ever want or need right out of the box. If its worth it, is up to you. But I feel that you should be comparing apples to apples.
And the stock urethane stock parts are not in the same league as the other parts mentioned above.