Way to go grasshopper! The old truckers shifting even works while at a dead stop, but that is where you can screw stuff up pretty bad. Just have to throw it in low and rev up just right to pop it in first. Could do it on my old 4runner.
The method of clutchless shifting doesnt really jack up the tranny like you think. Now if you grind all the time.... then yea. The synros may wear out a bit faster than normal, but on my fathers old '82 toyota PU, we did clutchless shifting for about 10 years and never had a problem with the trans....only the blue paint that never stayed on the hood.
The reason it works is because the syncros match up just right as certain RPMS (usually 3100k to pull out of gear and 2200ish to put back in..depends on speed/gear also) that make shifting perfect. It's not the best if you do it and every shift is a sudden tug, that could lead to problems. Downshifting usually is the trick place, especially while going into 3rd.
Have fun man, and just dont go overboard.