Rega P25, would it sound better than my CDP?

If you have an extensive LP collection I would say go for it, but you might do better with a Nottingham Analogue deck at that price.

If you have no LPs I'd say save your money and get a better CD player.

The difference in sound quality between CD and LP is significantly less than the variance in recording and mastering quality IMO.

(Owner of Rega P3 with Goldring 1042 and Monarchy Audio 22A DAC ... both about $1000 in their day).

"the idea that you should stick with the cd player if you don't have a vinyl collection is erroneous".

It depends. If you are going to drop $2000 on an LP playback system then that $2000 could seriously upgrade your CD playback, or purchase a lot of new and used CDs. If you have a $1000 CD player then you could upgrade to a $2000 player and have $1000 left over for more CDs.

This is really a personal decision with no right or wrong answer. Personally I would not stray into vinyl if I didn't already have a bunch of LPs. Used vinyl can be quite affordable, but the quality is something of a crapshoot, and you can't always get the titles you want. New vinyl is just way too expensive for me.

LPs are fun, turntables look cool, but I'm really not convinced they offer any significant sonic improvement over a good modern CD player.

Although I have no personal experience with the tecnodec or the P25 those in the know whose opinion I would trust says it is a lateral move.

If you're going to take the trade-in hit better to make a definitive move upward to, for example, a Nottingham Spacedeck, or a Michel Gyrodec.

I have always felt personally that incremental trade-ups are a waste of money, and it is preferable to wait until sufficient funds are accumulated to make a significant step up, or simply decide that it is not possible to justify a big jump.

Pretty sure this would be a significant upgrade:

http://cls.audiogon.com/cgi-bin/cls.pl?anlgtabl&1136034591

"Stylus drag is an instantaneous slow down of the turntable caused by tracking the record grooves."

Has anyone ever measured this ? The drag of a stylus tracking at 2grams slowing a 10 or 20lb platter (like the Nottingham).

Of course for every action there is an equal and opposite reaction, but this sounds a bit like the old physics example of a fly hitting an express train.