Which notification (sound, status bar,etc) was you having problems with?
I'm on my third Razr now & notification sounds for Gmail account for the blurmail app (the stock motor email app) doesn't work, I think I did status bar notifications though. Notification sounds worked on all accounts using K-9 (& various K-9 based apps) but push doesn't work on yahoo accounts. Gmail app seems to function well but is just to ugly to look at.
I'm currently using Maildroid, which your emails look nice like blurmail, notification sounds work for all accounts (can even set LED colors, status bar & vibration for each account), push works for yahoo, it supports split screen like Kaitlin(a K-9 based app).
Maildroid doesn't support swipe to next email like blurmail but does have arrow to next email(only in paid version which is over priced). Maildroid is also part of the long list of apps that go notification doesn't support but it doesn't seem to even work a lot of the time on ones that it should(Facebook). Also at this time Mobile Quickbooks won't fill emails with invoice info on maildroid (device is trying to see if something can be done on his side as he says QB has likely only set things on their end to fill K-9 based emails.
It doesn't seem like any email app does it all, but I really wish blurmail would give notification sounds for Gmail accounts as I like a lot about it's interface, but there's also a lot I don't like. It's great that it supports twitterbook(social network apps) in it's universal inbox box but I don't think I care for the drop box for accounts on the email part of blurmessaging, although it saves on user input when viewing default account it makes for more user input for us that have a lot of activity on multiple accounts. It's also not on the short list for go notifications. I did actually get Gmail notification sounds at one point but it was only during the time when I lost the ability to remove email accounts & I got notification sounds for all the other accounts at the same time no matter which account the new email was for.
With that said I think I'd probably just use the blurmail app if I could get the notification sounds to work on Gmail accounts. Hopefully this will be the case when we get ICS.
Sorry for getting a bit off topic & a bit long.