The A1 and P1S print identically for PLA, PETG, and TPU. The enclosure on the P1S exists for one reason: to retain heat and prevent warping when printing ABS, ASA, PA, or PC. If your filament drawer only holds PLA, the P1S advantage evaporates.
The CoreXY system on the P1S also helps with tall prints: the bed doesn't move on the Y axis, so heavy tall parts aren't thrown around. For anything under ~150mm tall this makes no practical difference.
Only if you use the enclosure. The P1S costs $100 more than the A1: $399 against $299, and that $100 buys exactly one thing: a box that holds heat in and keeps fumes contained. For PLA and PETG it does nothing for you, and the A1 is the smarter buy. If you expect to print ABS or ASA even occasionally, the P1S pays for itself in avoided warping and failed prints. Worth knowing: back when both machines sold at their old list prices the gap was $300, which made this a far harder call than it is today.