Take the 4stroke displacement and convert it with this formula. Divide by 3 and multiply the result by 2. Example: the 61FS would be 60/3=20 and 20x2=40

So you want more power and figure to use a 61FS. That 61 is going to give you the power of a 40 two-cycle. More power? Not that way.

You want performance? Power isn't the only way. Lighter weight helps performance. Consider engine design and weight. Look at a 4stroke and all it's parts. See all that stuff on a 2stroke? All that stuff weighs something. And isn't on the 2stroke. So not only is the 4 less powerful for a displacement, but it's also going to be carrying stuff that makes it weigh more. OK....... what's left on your list...........

Plug and Play......... chuckle...........
The valves on a 2cycle are holes in the cylinder walls. Do they ever need to be adjusted...... nah. Do they ever get out of adjustment......... nah. Do they add to the cost of the engine..... oops, wrong topic. But no, they don't.

How easy are 4strokes for beginners...... We got two in the last few months who tried 4s on their 2nd airplanes. Both have ruined those 4s with bad needle settings. Why did they set the needles wrong........ They didn't want to buy a tach because the 4s cost them so much more than 2s would have cost. And 4s are harder to set by ear. And their ears hadn't learned to hear what almost can't be heard, the change in pitch that 4s don't do but 2s do. Heck, we got a couple of flyers who've flown for years who've ruined 4s just in the last year. They wanted to try them and did.

Reliability was a criteria.......... whadda you think after reading about the complexity deal. Which is going to be more reliable..... a simple device or a complicated one.

Can all these things be overcome...... you betcha.
Would it be possible for a newbie...... you betcha.
Sensible to expect success doing it.......... hmmmmmmmmmmmmmmm

Actually, you can't overcome the weight penalty. Or the power loss per cubic inch. Or the added complexity.

Why was it you wanted to pay more, get less power, have to fly more weight, have a harder to handle engine??????????