That does appear to be a better ratio by a good bit, but is it worth the infrastructure costs? Piece together a system that, by itself, equals X amount of electrical engines, and then price it out piecemeal for us, so we can compare that way.

After a bit of figuring, at this level of output the price of a steam boiler can vary greatly in competetiveness (sorry I don't have spell check at the moment) based on what upgrades you give the electric engines. However, the overall summary is that with electric engines, the better you make your ratio, the more resources you'll require.

For example, let's say you wanted to match the output of a low pressure boiler. That's 72 MJ/t. Now, if you wanted to maintain the very best EU -> MJ ratio, which is a single basic circuit board with one iron electron tube, that means you'll need 36 engines, 36 circuit boards, and 36 electron tubes. Per engine, you'll need 12 tin, 2.2 iron and 7.5 redstone, assuming cobblestone and wood are infinite and thus trivial. So that's 432 tin (6.75 stacks), 79.2 iron (1.2375 stacks), and 270 redstone (4.21875 stacks). Double these values, and you'll match a HP boiler in output.

And it will cost you 180 eu/t.

However, since you probably won't have infinite resources if you're comparing different systems against each other in terms of resource cost, you probably will want to reduce that down with better upgrades. A notable combination is a tin and iron electron tube in enhanced circuit boards, which halves the amount of engines required, and the per-engine costs to 12.5 tin and 4.5 copper, with iron and redstone costs remaining the same. This is 225 tin, 81 copper, 39.6 iron, and 135 redstone, and double that for a HP.

This will cost 216 eu/t to match a LP boiler, double that to match a HP boiler.

I could go on, but I think you should get the point that with electric engines, increasing resource efficiency leads to decreasing energy conversion efficiency.

Now, unfortunately, the math for the boiler system is much less pretty then with the electric engines...

First, since I don't have access to the game at the moment, I will go ahead and state that I am assuming it takes 37 seconds and 93,000 EU to create 4 hydrogen, which creates a total of 8000 heat value in a boiler.

This means that each electrolyzer is capable of producing enough fuel for a max-size, max-heat HP boiler for approximately 25 seconds of use, which means you will need about 1.5 electrolyzers per HP boiler, and half that for a LP one. If someone else could be so kind as to audit all the resources required for one electrolyzer I would greatly appreciate it, but I would estimate around 32 iron, 10 redstone, 12 copper, and a few other odds and ends.

Additionally, both boilers will cost exactly the same in terms of iron until you reach the engines, which I will assume you use industrial steam engines since they are more resource-efficient, in which case you use half as many engines for a LP boiler then a HP one.

The boiler + fireboxes will cost 96 + 51.75 = 147.75 iron. Industrial steam engines cost 13 iron each, plus 1 redstone (which I won't count since that's generally a negligable amount). It takes 18 engines to fully use a HP boiler, so that's 234 + 147.75 = 381.75 iron in total (5.96484375 stacks), for 144 mj/t. For a LP boiler, it's 264.75 iron (4.13671875 stacks) for 72 mj/t.

According to my calculations (93000/8000), every point of heat value coming from an electrolyzer is equivalent to 11.625 EU, and I also know from previous calculations that a HP boiler requires 16 heat units per tick, while a LP requires 8. Which means that a HP boiler will require the equivalent of 186 eu/t of hydrogen to make 144 MJ/t, while a LP boiler will require 93 eu/t of hydrogen for 72 MJ/t.