This IS a tough question.
you have already been given great advice.
for me there is no across teh board answer.
the answer depends on the child and you.
i say this because sometimes i DONT listen to my child. i DONT allow her even though she is willing - because many times she has no idea what it means she wants to do. its a tough tough decision and many times i am not sure if i AM making the right decision or not. there have been times when i have allowed dd to do something which she wanted to do, and she regretted her decision. so its a work in progress. for example at 7 i became super strict about how dd showed her anger towards me. i didnt care of how she showed it but she did. she would be down for days regretting how she treated me. she is her worst critic so i have to sometimes save her from herself.
but it would depend on how emotionally mature my child is at that moment, how strongly she feels about it and how sure I myself am.
at 5 dd was there at both her gparents passing. she WANTED to be there. she needed to be there esp. after helping take care of them since she was 4. it was healing for her to be present at that. she held their hand and patted their brow or sat silently next to them as they passed. after they passed she read them a story. and then she helped wash them and dress them before they were taken away. she was SURE she wanted to be. i was SURE i wanted her to be there. it definitely, definitely helped with the grieving process.
no matter what your decision - a formal goodbye is VERY important. most kids need a closure no matter what age. a memorial service is a great way to do it. dd had one for her hamster at our place of worship. people came in an amused way to support dd, but left moved as they witnessed dd's expression of grief.