I've got a little bit different take on this, I think. Get rid of the fiddle blocks. They don't belong on a mainsheet set up. You don't really even have a 4:1 purchase with those inside blocks that have a smaller radius (smaller radius - more friction). You absolutely need more purchase. Even for your boat, I would use 6:1 by using 2 triple blocks. I did that on my Starwind 27 and it was a huge improvement. Sue always has a problem releasing a cam cleat under load because she always tries to jerk straight up. When you pull out and up (or down, whatever) at the same time, it is no problem.
Line friction in the blocks is not an issue when you select the right line.
Dumping the traveller is usually effective in righting the boat with a lot less noise and commotion than releasing the mainsheet. Also, the trim for the main remains unchanged, so it is easier and faster to get underway again, just pull the traveller up.
Obviously, there are reasons to adjust traveller rather than mainsheet but I never did buy this argument. When you need to dump the main sail on a small boat (ODay 25), I think it is more beneficial to dump the mainsheet. First,
@Project_Mayhem already says there are more difficulties in reaching the traveller. I had the same problems with my Starwind until I modified my traveller, so I get it.
Other than that, though, when you dump the traveller, you are more likely to foul the leeward lines, making it a mess to restore the setting. Just last week when Sue and I were doing a series of jibes, she kept fouling the leeward traveller lines, making it necessary to pull out from the windward side to take out the snags. Dumping the traveller rapidly causes the same problem.
Besides that, there is no difference in restoring the setting of the traveller when you dump the mainsheet. In fact it is exactly the same or even less troublesome. Basically, you don't have to do anything except pull the mainsheet back to the original position. You haven't changed the trim one bit after you restore the mainsheet. So, in ideal conditions, there is no difference. Under circumstances where the traveller either fouls or is more difficult to handle, it makes more sense to dump the mainsheet.
When you need to dump power in a hurry, the mainsheet makes a big change to the angle of attack AND twists the main simultaneously, which is exactly what you want to dump power.
Sure, adjusting to a puff or change in wind direction, use the traveller.