Okay, should you decide to upgrade to LE 6 then you will definitely need to go for the Pro option to allow you to continue capturing your analogue sources (and to be able to capture uncompressed HDV at a later date when you need to). LE 6 Pro comes with BoB which permits all this plus allowing you to preview directly to a monitor even while rendering.
If you seriously plan on editing HDV then you will need quite a meaty system at some point. A well-specced PC (3.0 GHz, 1GB RAM 2x 160GB HDD) will suffice for editing 720p (up to around 5 layers), but you need to be looking at a dual processor high-end P4 with oodles of disk space to edit 1080i.
If you already have a system capable of editing DV adequately then LE will make this a blast. LE's performance is superb, as is it's stability and fact that it's almost impossible to lose any work due to the InstaSave feature.
LE does support DVD authoring directly from the timeline and comes with over 40 templates. Infact in the package you get:
Liquid Edition 6 Software CD
* Liquid Edition 6 software
* Liquid Edition Start-up project
* Pinnacle Hollywood FX™ Plus RT
* Pinnacle TitleDeko™ RT
* 40+ DVD templates
* 1,000+ real-time effects and presets
* Liquid Edition Reference Manual on CD
You can also import your Studio projects directly into LE 6 as well as all Studio plug-ins!
With regards the learning curve. Yes it is naturally steeper than Studio's learning curve. However, it's enjoyable and the more you learn the more you realise the power and extensive versatility behind the software.
I can't say whether upgrading is the right choice for you, but I can say that if you did - you wouldn't regret it
Oh, and the Pro BoB looks really sexy - that's the clincher