Overgrown tracks look great, I usually keep mine clear because I found that the small details of the train were being swept off the loco. I am still looking for a whistle lost off my lgb 2-4-0 after 4 years. Also at times the loco stops because it has fouled a low branch that wasn't there last week. I always run my least important loco on first lap of the day. Even after eyeballing the track I still can miss things & better to find a problem with older trains than derail or damage the good loco detail.
I like the baby's tears though, so I might give them a try in the outdoors part of the track. I presume they need part or full shade?
Also as my layout is at places 4 foot off the ground, it would be my luck to fall off and break a leg. How would I look in hospital when I told them that I was peeing on the track when the accident happened!
Regards from Andrew at Sandbar & Mudcrab