Several years ago I had a Pegasus XL with a 447 engine. I loved it and, when I've saved up enough pocket money, might buy another.
The XL wing is thoroughly forgiving to fly - even more so than the later Q wing and, as an added bonus, has less batons and so is quicker to rig.
The later Q wing has a wider speed range and that could be useful if you're trying to make progress into a headwind. Having said that, I used to go places into the wind with my XL - it just used to take longer.
The 447 engine was not particularly powerful. The upside though is that it's very simple to maintain. It was fine with either just me or a slim passenger but with my fat friend in the back seat the climb rate was awful. Some XL trikes have the more powerful liquid cooled 462 engine which might be a better choice if you regularly have a passenger or are heavy yourself. I've an idea that there were also two variants of the 462; one higher power than the other - though I may be wrong about that. The downside of that is, of course, an extra thing to worry about when servicing it - taking the cylinder heads off the 447 is trivial. The air cooled 503 engine produces power somewhere between the 447 and 462 but I don't remember it being available on the XL (Q) trike though, again, I might be wrong about that.
The trike, which is common to both the Q (combination called the XL-Q) and the XL (combination called the XL-R) wing configurations, is very cosy when you have a passenger. Where I learnt, the instructor had a Quasar which is a Q wing with a much posher and more comfortable trike. Quasar's got cheaper after Pegasus brought out the Quantum and so, if there's one available when my pocket money is saved, I might go for the extra comfort. I don't suppose that they'll ever get as cheap as the XL-R though. My instructor's Quasar had the 503 engine in it which seemed to work OK for the both of us.
The conditions that you might choose to fly any of the wings (XL, Q, Q2) are similar and I don't there's any conditions where it would be safe to take one and not another. The pilot's experience is a far more significant factor.