Why’s there always BEEF guys?! 
I’m gonna put a little input on this, since I started playing A-sak now, and I have had some talks with Apoc and King about this subject.
Let’s examine by just groove, and not character specific.
vs. C
C just builds bar too fast. If they are empty, it will take at most 4-5 rotations til they have 1 bar, and then GC ya. So it really isn’t a good idea in this situation. However, if you practice cancelling a DP into a roll when you see the flash, you can catch avoid the cancel and possibly reset your combo (it varies upon characters), you just need to practice it (Apoc makes it sound so easy -_-)
vs. A
If you’re playing against any decent A-groover, they will counter activate and get a free 8k or so on ya, so I really don’t suggest burning it in that situation. They also have the option of GC’ing so it’s still iffy. I would wait for them to activate and counter activate.
vs. P
Well, depends on how good the P-groove player is. I’ve had the computer parry my opening low hit of a combos and DP/Super me quite a few times recently, so theoretically a good P-groove could do the same. A little FYI, I normally won’t burn a P-groove player because of the amount of bar they gain from blocking the combo. P-groove will get a full bar out of a blocked combo. But if it will kill a main character (r2, sagat, random top tier) or they already have near to full bar, Burn that Shit. 
vs S.
This ends up being similar to C. S will build bar as blocking and just GC. Or dodge the first hit and depending on the character, hit you out of your combo (examples of this are character’s that have a ‘hop’ style dodge attack, where they leave the ground such as Guild and Chun Li, they will go over the initial low hit (if you go low, I normally do) and hit you out of the combo)
vs. N
A smart N player, will counter roll early or counter hit. Kind of a guessing game, but Dp cancelled to roll by you will at least put you on even ground.
vs. K
From what I hear, Ino (best K-groove player in Japan?) will just burn a super upon A-groove activation. If they aren’t raged I suppose it’s possible to JD the first hit and DP or something, but it’s not exactly the easiest thing in the world to do. This is by far the best groove to do the block cc.
On a general note, I like to activate when the guard bar fairly low in the first place, usually done by block strings (either cross-up mk, wk, wp, wk or rc’d hurricane kicks cr. mp rc’d hurricane kick etc) Or you can throw in a random roll -> activate low hit, and hope to catch them off guards.
Hope this is of some help.
Their guard meter when you activate and their bar at the time is also a factor, because obviously you are going to hit them with some s.rh, rc.hurricaine kicks, other pokes. i’ve guard broken an n-groove before they got bar, I dont remember how much guard i had already taken off though.
edit: oops! i didn’t finish reading the post before mine 
Do you think it is good to intentionally take a counter hit to drop their block guard more? or does it put you in too much of a defensive position to continue guard break.
Cancelling into roll when you see the flash sounds like it might take me some practice But it would be awesome if i could get it, hehe