Has anyone used Transcend Flash IDE DOM? or Similar Flash IDE (DoM)?
Are they any reliable than standard HDD IDE drive? Did anyone had any problems with it?
Surely flash media is much more reliable in regards to physical reliability - shake it, knock it, break it 
And as there are no moving parts etc., reliability is one of the big advantages of those flash disks. We run almost all systems from IDE-Flash (where not using a CF).
But you should be aware of one thing: Every flash media has only a limited number of write cycles for each memory cell. Granted, the numbers quoted by the manufacturers are quite high, but you should be aware of it. That is, it can be possible to “kill” a flash media by writing often enough to it. There’s nothing you can do against it. (Manufacturers of higher quality flash media incorporate technology to “dim out” corrupt memory cells and transparently replace them internally by “spare” memory cells.)
I myself only have lost one of those in the last few years, and that was a test machine which really had to suffer from daily re-installs .
There is a number of threads here in the forum (or was it back “in the old days” on the mailing list?) about RouterOS and writing to the flash media. Current versions of RouterOS try to do as few writes as possible to disk (i.e. to the flash in this case), and I suppose you’re not going to experience big problems.
But please do NOT try to use a big flash disk (like 1 GB) and use this as a proxy server cache (like one of my customers tried to do…). This will surely kill the flash in no time…
if one would take a spoon, and went to a house - surely he could be able to destroy it with that spoon. but how much time would it take ?
surely an exaggeration, but not far from truth 
be have been using those modules for years and I haven’t seen one that has worn out.
Thanks for the advice, guys. Is there anyway you can tell how many cycle it has written? I’m getting 256MB Flash IDE for bandwidth queuing and firewalling, will there be any problems with write cycle? I also do a lot of packet sniffering in firewall too to hunt down hosts with viruses and worms.