I am not a local to the Hood scene to I can't comment too much on your progression. But I can help compare to some other routes in the Cascades that you listed. First off I want to say that many of these routes can be in a wide variety of conditions based on the year so take that into consideration.
I have climbed S Side Old Chute/Pearly Gates as well as the Reid Headwall on Hood. I have also done NE Couloir on Colchuck, Triple Couloirs on Dragontail, Kautz on Rainier, N Ridge of Baker and NW Ice Couloir on Eldorado.
Obviously you are familiar with the Old Chute on Hood so I will base things off that and go through them in order of difficulty.
The Reid Headwall I solod in good condition and felt very comfortable. We roped up for the glacier down low then solod the actual route and skied off the summit (down the south chute). I felt like the actual route was similar to the steep section of Pearly Gates route just for a lot longer. It felt very secure soloing with 2 tools.
NE Couloir on Colchuck was similar to the Reid Headwall in terms of difficulty. I did it in May when it was in good fat condition. I took my wife who wasn't comfortable soloing and we did a simul with a couple points of running pro in places. Just good steep snow climbing.
NW Ice Couloir on Eldorado I did in April of a fat snow year. As such it was all snow and zero ice. I would not recommend. We simul-climbed the couloir in 1 block and found the crux to be at the top where it was vertical snow the consistency of cotton candy. Not hard enough to climb well but not really easy to clear either. Very challenging conditions for 20ft with marginal gear. Most of it was similar to the 2 above routes but with a much steeper/scary exit.
Kautz Glacier was done in June. We had great condition and a fair bit of steep snow and less ice. I think it would actually be a fun ice climb later in July but by then the other parts of the mountain are typically so baked. We simul-climbed as two parties of 3. The leader on the first rope put in screws and the last person on the 2nd rope pulled them out. It was only a couple rope lengths and it felt pretty casual. That said I am very comfortable on vertical ice so this was chill in comparison. It might approach a WI2 pitch in thin years in July/August but in June it wasn't even close to that.
Triple Couloirs on Dragontail I climbed in March of a fat year. We solod all the steep snow couloirs. They are steep but the snow was great and felt very comfortable with 2 tools. As I remember, the 1st couloir had the steepest snow sections particularly getting into the entrance and 1 point halfway up where it narrows had a steep section. We pitched out the ice between the 1st and 2nd couloir. This ice felt very much like WI3 climbing. Plenty of good ice for gear or nearby rock. Lots of places to rest but terrain I would not want to solo. We did solo the mixed step between the 2nd and 3rd couloirs. We probably shouldn't have but we weren't really paying too much attention (just going up) and didn't realize that we should have pulled out the rope until we were in the middle of it. At that point it felt easier to just keep going then try and reverse course and pull out the rope.
North Ridge on Baker I climbed in July. I feel like this route changes from year to year as the ice cliff changes. We found lots of steep snow climbing below the cliff (similar to above mentioned climbs) that we solod. Then we had the actual proper cliff and terrain above and below. We did 4 pitches of pitched out climbing. We could have done it in fewer pitches but we didn't have enough screws. We had assumed it would be a short steep step but it was much longer. Here are a few notes from my journal I wrote 10 years ago.
"Made it up to the crux ice step and had to take a 2nd look. The easier left hand variation is supposed to be a 60-70 degree ice ramp. What we found resembled rock. There were cracks and corners, ledges and ribs and all of it on 100 feet of 80° ice! He [my partner] led a short pitch of 60-70 degree ice up to the steep part. We only had a 30 meter rope and 6 ice screws because we thought it would be easier. This meant we could only place 2 or 3 screws in between belays. I tried to run things out and led two pitches of ice. Then he led a little more to the crest and onto the steep slopes above."
Anyway hopefully that helps compare them a little. Good luck with your climbing progression!! Just remember that a lot of people (myself included) solo a lot of steep snow on these types of routes. But everyone needs to evaluate the pros and cons of such a move. There are lots of places were a fall would be very painful if not deadly. However if you have to move through 2000 vertical ft of terrain pitching out that much will take a LONG time. There are pros and cons to everything and just because somebody does it one way doesn't mean that everybody else should follow suit.