Frederick,
Both engines are in the older large case, right?
In the 1980's I campaigned their grand-daddy, the big-case 40 BB Schneurle. I found that tank position was critical, and unconventional... Once 'tank height' was settled, the engine ran just fine in low-2 cycle mode with muffler pressure. 11-4 or 12-4 props, 10% nitro fuel. 20-25% oil (I used all or mostly castor, but as a Dykes-ringed, BB engine it could probably do as well or better on today's standard 10/22(50/50) blends.)
Couple of other tricks made it a fuel-efficient and smoother running engine - which may not be needed for the recent 45/46 engines - and it lasted for 450-600 flights, with some left over: the plane broke, not the engine!
Yeah, they are heavier, and the mount pattern is unusual, but they are good, solid and durable engines. It just takes a while to dial in the tank height, prop, plug and fuel. Once you've got that, it's a set and forget, long-lasting situation.
If you have either one, make sure there's plenty of room to jack the tank around, and spend the time to nail where it should be. After those 5 to 10 flights (at most - OR use my patent pending wing wig-wag check for getting it right before first flight...), playing with prop and plug will only refine a fine set-up.
If you DON'T have either engine, it IS simpler to go 46LA-S of the equivalent, and probably less expensive. But, then, where's the challenge???