Take this scenario > using Panasonic DMREH50:

I record a 2 hr film onto HDD using SP then dub to DVD-R using SP:

Film gets compressed to SP on HDD
Straight transfer of data from HDD to DVD-R

whereas:

If I record a 2 hr film onto HDD using XP then dub to DVD-R using SP:

Film compressed to XP on HDD
Film compressed again to SP to fit onto DVD-R

So, in summary it looks like the first option is the best because there is only one lot of compression.

Have I got this right?

If you record a 2 Hr film in SP on the HD, you can fast dub to DVD (about 15mins) to a DVD. If you record in XP then want to compress to SP on DVD the dub must be in real time. In fact in the latter case it may be better to dub in Flexible mode.

I'm no so concerned about the speed of dubbing, its more a case of whether there is multiple encoding taking place.

If so, then there is little point in recording a longer-than-one-hour film using XP if it's only going to be compressed again on transfer to DVD.

That was my conclusion too. Frankly for normal viewing I have not seen a difference so SP is the way I record everything now.

XP is not compressed,it offers full quality.
The way you should do it,is if you know the running time of the finished recording after editing,then make the recording in the correct quality on the HDD in the first place.
No additional compression,and it enables high speed dub.
If you are unsure of the end running time,record in XP then dub in real time to DVD .
Although on paper you may be losing quality,you won't notice it

XP is compressed. It is MPEG2 and has a bitrate of about 1.3MB/s (4.7GB/hr) which is much lower than normal uncompressed video and about 1/3 of mini DV.

I see what you're saying about guessing ahead of time and then recording in the right mode to start with. It would appear the best thing to do rather than multicompressing the signal. Pity the instruction manual doesn't tell you this