achieve: heh - GO GET 'em, Tigresse!!
Here's a true story from own experience, that I had almost forgotten, but suddenly remembered following your excellent post, in picking opposition that force you to "stretch"
I remember in my preparation for Seoul, as I had no real competition in Holland, who were essentially my team-mates, and I was national champ, that "we" were able to arrange a sparring-partner for me that could push me to <go and search for> that illusive edge, extra speed, that I needed to be able to compete with, and beat, the absolute top level from players from France, Sweden, Finland, Germany, Asia... So I spent two weeks at an aunt's house who lived near a guy who was absolute able bodied top in Holland, premier league player here, and I got whupped pretty bad at first, all games 21-15, or worse for me, but I was forced to adapt, and simply find a way to compete with him, as I could feel and sense he wasn't more talented or creative with the ball, but he just had at least 10-20% added leg speed, movement, and therefore incredibly grooved topspins, fast ones, off both wings... So I started to speed up myself, I needed to, lower my position, knee bend, and didn't care if I lost 10 out of 10 games we played a day, in the first week, but at the end of week two, I cut in to the ratio and got it down to probably 3:1 - 2:1, still in his favor, making him the favorite, still, in any best of five if we'd play. But at least I felt I had gained ground, sharpened up many aspects of my game that hadn't improved that much in years, and really that two week training camp had gotten me in the right frame of mind to play extremely sharp, within my control, in Seoul, with "surprisingly" good result.
Most important was the air of confidence that i had gained, and was able to take with me to Korea. It was only a matter of being able to control the mind and nerves, in order to be able to dig up what I "knew" was in there...
The fact that I "knew" it was there, firmly believed in it, is what gave me the edge. That confidence can even make you beat a "higher rated" - if the guy gets rattled, if you start shakin his "bonbons", those guys could tense up and were really rolling over like puppies, because they'd lose confidence in the abilities they had.
Sounds tough, but if you smell blood, and go after it like a rabbit badger, the so called top dogs can go off the boil.
That's why sparring against an engine is valuable, but never will they go off the boil. Never.
Humans do, without exception IMO.
Conclusion:
As long as you pick players that are intrinsically stronger than you (which is hard to do online as you explained - I hope Yahoo *does* provide that pool of players for you), learn to spar with them, live with them, even if you lose every game, you'll be closing in on them, without even being aware.
I was lucky though, that we were able to find a guy of relative 2600 strength, where I was say 2400/2450, and spend TWO WEEKS functioning as a sparring robot, which is much harder in chess, to find someone, or the plural, to be there - daily - for 3 to 4 hours a day for sparring.
Point is that you want the serious sparring at 30 mins a game minimum, and not the 10 mins or faster format.
Anyhoo, 't can be fun reminiscing, and it illustrates the importance- and luxury- of being able to play and train against stronger opposition, dragging you out of your comfort zone, forcing you to <find ways> to close the gap, if possible, or at least learn to live with the temporary, "uncomfortable", situation.
Not many have the balls to undergo that, and it becomes harder and harder with advancing years, but eg Jacob Aagaard, prolific chess writer, managed to get his GM title well in his thirties.
Actually - to have the silly engines as super slaves, is quite an advantage in many ways, to other sports, and to make good use of them is quite a challenge, but they are at your beg and call 24/7 - though not a lot of fun to talk to.
Well - that's what our CHESS AHOY friends are for.