A few things to note:
- As shown, you have "suicide biasing". In sim, hFE and temperature are fixed; in practice, they will differ between parts, and temperature will vary over time. This is harder to simulate. (SPICE was developed for working with integrated circuits, where equal temperature is a safer assumption than for board-level components!)
All models in a sim are perfectly matched, so you'll get perfect matching regardless of topology, of course.
You can start to get a more realistic idea of this, by customizing the models for each part; or using a Monte Carlo simulation (varying hFE or whatever). I don't know how to do this in LTSpice offhand, but check out further reading along these lines, ought to be something useful out there.
- This is easily fixed by putting a divider resistor below R2, and optionally, tying its top end to collector(s) rather than +V (so it gets some DC negative feedback from the output). Often some (AC) feedback is done intentionally this way as well, as "neutralization", i.e. using an intentionally relatively low value for R2. (That's not actually neutralizing any reactances, it's a resistance, obviously; it's really just flattening the amplifier's response, trading gain for stability. It also burns some power, as the value usually needs to be low enough to steal a substantial fraction of the output [some percent], which might not be ideal if you're going for a high efficiency amplifier. So, it trades off several things together.)
- Nodes are ideal, so there's no stray inductance between transistors, or capacitance to ground. You may see a stable simulation, which isn't even constructible in real life because zero stray inductance and capacitance implies a circuit of zero dimension. The fact of the speed of light, manifests as equivalent inductance and capacitance in a lumped-element circuit like this.
If your transistor models have package parasitics included, that's a start; you can further enhance the model by adding L and C between transistors, corresponding to the particular PCB layout you intend to use. (So, depends on topology, if you've got a block of 'em in parallel, or routed in a (linear) chain, etc. Coupling between inductors would also be interesting to model, but quickly gets very complicated to express -- and measure!*)
*There are, in fact, tools to do this; but they're all enterprise-grade, AFAIK. Example, Ansys has a PCB field solver tool, which extracts a coupling matrix corresponding to a real physics-based model of the PCB. It also costs six digits $... (Probably, the 4-5 digit$ ADS and such, can do the same as well? I'm not very familiar with them, alas. Great way to go, though, to construct that pesky "10n" on your sheet -- which might be a mere cm of trace length, but what exact length and width, now, that's the question!)
Anyway, adding some strays, hand-wavingly representative of some layout you have in mind, might not be a bad idea for getting some idea of bandwidth and stability.
Which, as for that -- all the amplifiery things we do in RF, have to be constructed in the sim. Read up on the definition of source and load ports, reflectance, etc., and construct bridges (or postprocessor expressions to the same end -- in AC analysis anyways, else you'll have to construct the full thing for transient analysis) to measure incident and reflected power, phase shift, etc.
Tim