THX vs. DTS

Hi.

I would like to get opinions on experienced ears who have had THX and DTS systems. I am thinking of getting a new receiver, perhaps a Denon and considering upgrading to THX. The problem is of course, it cost a heck lot more.

Does THX really make THAT much of a difference (2-4X the money!). I don't see many DVDs with THX around, is DTS enough for the next 5-7 years? I like DTS already.

Thanks.