Actually define stronger...
Longitudinally
In compression / torsionally ?
The H is stonger in a bending moment through the two beams.
The most important factor for the rod would be in compression as, correct me if Im wrong that where most fail.
Rods usually fail in tension as result of trying to stop the piston hitting the head at high RPM. Compression loads are pretty easily assimilated unless you are looking for the ultimate in lightness at modest RPM'S.
Although the stock RB26DETT rods are strong they use a rather dated method of retaining the big end caps, bolts and nuts. I personally think a lot of RB rod failures are really bolt failures, it's very easy to install a shouldered bolt into the main part of the rod wrong, and either nick the corner of the rod to leave a stress raise, or to install the press fit bolt wrongly clocked, so the oval head is cocked around and not sat securely on the flat of the rod. In use the rod bolt rotates a fraction to fully seat, and loses tension, then BANG! Modern thinking, save in Ti rods where bolt galling is an issue, is to use bolt that threads into a female thread form in the upper part of the rod. These are inherently more reliable as you lose half of the interfaces.