Well, they're not my "go to" mics (which are AKGC451EBs). However, the AKGs were several times the price of the SE1As I have--and I only have five of them. The SE1As are close enough that I use them happily if I need to put the 451s on something else--before retiring to Aus, I was lucky to live about five minutes drive from the UK distributor for SE and was able to borrow a pair and do an A/B comparison with my 451s (and also some AKG 391s)--they were close enough and good enough that I bought them. Indeed, if I had to characterise the sound, I found them pretty close to the AKG 391 "Bluelines" if you've ever heard them.
In sound quality, they are nicely detailed--perhaps not quite has much as the 451s but darn close but manage to do this without harshness in the upper ranges which can be a concern with SDCs. SE do a matched stereo pair version of the SE1As but mine are just the standard ones--however their quality control is good enough that I've used them for X-Y stereo miking with no problems.
I've also used them live, both on guitar and as drum overheads with good results--the polar response can help in feedback rejection in live work.
Anyhow, hope this helps.