I use Remember the Task on my Linux desktop and netbook and it works quite well.

Adobe Air will no longer be an option for Linux desktop users as it is no longer developed for Linux. "Remember the Task" would not be a good option.

I am currently trying native apps like "Getting Things Gnome" and "Tasque". Neither of them are suiting me well though :(

I have a pro acc't, and I feel there should be support for ALL mainstream OS and e-mail/calender clients.

I completely agree with capemayal. There should be a Linux client given that so many people are using it.

I agree.

Tasque is okay for viewing tasks, but seems incapable to complete them correctly.

A purpose-built Linux application (for all distros) would be great.

You have my vote.

Tasque is ok but still in early stages of developing...

My wife and I have Ubuntu, Mac, and Windows machines. Native applications for each of these OSes would provide opportunities for pop-up reminders, spoken reminders, and offline task management.

I use it constantly on my win down tablet, but the need for an internet connection really slows my productivity. I'd love to see a desktop version!

Getting Things Gnome disable plugin for RTM. But it will be enable in 3.0 version. They are working on it
Tasque is baggy

I tried Tasque, gmilk and Getting Things Gnome but none of them worked very well on Ubuntu. I mean, if you just check tasks then they're ok, but it's hard to manage them. ( BTW, Tasque is relatively good, both in UI and function.)
RTM should consider developing desktop apps for Linux because sometimes we really need to deal with tasks offline.