What is the conceptual difference, or difference in nuance between these two constructions when used to mean 'and'? I realize there are some syntactic differences, such as や not appearing after the final item being enumerated, but as far as general nuance is concerned, is there any significant difference? For example, here's a couple sentences:
1a. 怪我やらインフルエンザやらで、試合に出られない選手が多い。
1b. 怪我やインフルエンザで、試合に出られない選手が多い。
2a. 今日は会議やら新人研参会やらがあって無理。明日なら大丈夫だけど。
2b. 今日は会議や新人研参会があって無理。明日なら大丈夫だけど。
Is there any difference in meaning in these (or perhaps other) examples of usage?