I have mix and match stuff too - especially with an orange wheel and a pink sputnik lol! Our hamster doesn't care either
I just like items that don't break too often and need replacing. The ladder thing is just a safety thing - people on here tend to recommend filled in ramps or tubes/tunnels instead of open rung ladders, just in case of injuries. The bendy bridge ones are quite practical although even they need checking for any large-ish gaps a hammy could get a foot stuck in.
I quite like mix and match anyway. I had to chuck away a few things recently after a horrible moth-hatching incident, so Charlie was short on toys - so he now has a pink egg cup and a heart mug in his cage