While I respect Jon's opinion immensely, I can provide a bit of a counterpoint.
If at all possible, I would see if Scamp
can provide the names of owners in your area with both sizes of beds and see if you can ask the owners opinions and respectfully and carefully try actually laying on them.
My sister (& BIL) had a Scamp16 Standard with the 44" bed and my wife and I had the Scamp
13 with the larger 54" bed. My sister thought that the 44" bed was "pretty snug" and liked our 54" bed a little better. They eventually got an Escape
17B with a larger bed.
Many folks have made the 44" bed work for years and, like Jon, may even prefer it. Jon is absolutely right that the space for the extra 10" of bed has to come from somewhere and the 22" wide closet becomes a 12" wide "pantry".
With either bed, remember that the curved back wall of the trailer means that the person in back won't get their full half of the stated width.
Many people don't like the "crawl over" attribute of either bed ... especially in the middle of the night. If either party snores at all, becomes ill, or needs to get up frequently at night, the extra 10" of bed width becomes a little more appreciated.
My wife and I sleep in a larger bed at home (king, although a queen size would be plenty), but we've often slept in a double (54") on our infrequent trips overseas.
Perhaps because we are no longer young and slender newlyweds, we like the 54" bed. However, it really depends on what YOU like!
Best of luck on your decision(s)!