Assuming this version of Labour is similar to the last version of Labour which won an election (and the only one which possibly could win an election), would you say the previous version of Labour were comparable to the Tories who have been in the last 12 years?
Lets clear this up though, the Tories have chopped your arm off (and done much worse to many others) and it ain't coming back under the Tories that's for sure, and like
@MolteniArcore says, you're literally not voting against them doing it again.
How would you feel if the Tories won your seat by one vote, or even 1000 votes if some others like you did the same. Then repeat that all over the UK.
It just seems a waste of a vote, and you've clearly got an interest, as you're posting on this thread. At least the people who never vote, probably don't have a clue about what the hell is going on, or just don't care, so can't expect them to do anything either way.
I'd trust Labour to stick to their manifesto, providing nothing exceptional happened, but then even if those things did happen then they would largely stick to it then also, where possible.
When Labour have been in power previous, do you think they largely stuck to the manifesto or not?
I think the doubt you seem to have is they never stuck to the previous 2019 manifesto, but that manifesto lost by 365 seats to 202, and the world has been turned further upside down since. That manifesto, the Tories and brexit cost you your arm, I don't see the point in sitting on your remaining hand whilst the Tories polish their axe ready to take the other one.
In hindsight Corbyn probably shouldn't have been there in the first place, he and the Labour members etc should have realised the UK wasn't ready for what he was proposing or what the members wanted, he was leading them down the garden path to something which was unelectable. You can't appease the left too much to a point where it loses too much of the middle. I wonder if this also led to more of the centre and right panicking and voting to leave, or if Corbyn's Euroscepticism or luke warm support played a part in that.
Once the UK (England) voted out things were only going to get worse, the country clearly jumped further right, moving the balance even further from JC. 23/31 of the shadow cabinet left within two weeks of the leave vote, and then he lost a vote of no confidence by 172-40. He should have walked.
He had a second chance to walk after he got beat by May, who wasn't doing a great job, but there wasn't much point then, and I suppose him sticking around for the next loss gave us something to draw a line under, and at least the new guy doesn't get associated with two previous losses. I don't think the last loss would have been anywhere near as large mind, but we've made it back up just fine.