650b or not to be?

MTB noob

I've had a feeling for a month now that I'm getting a bit big for my bike and I just want to try something new. My existing bike isn't the best for my money but I've tried to make it work. My attempt to make it a hardcore hardtail has failed and it only made my bike front heavy and the ratios are too small if I go downhill. I have really messed up everything on it. On the other hand it makes a really comfy ride along the south coast.

Some tech specs (weights are approximate):

Frame: Voodoo Bantu 18" - 2000g
Fork: Rock Shox Tora 302 - 2300g
Wheelset: Alex TA19 on Deore - 2500g
Tyres: Conti 2.4", 2.2" - 1225g (both)
Brakes: Shimano M446 - 800g
Drivetrain: Deore HT2 with BB: 950g
PC980 casette on xtr chain on SLX Shadow mech - 280+280+280g
Bars: FSA XC281 680mm - 300g
Pedals: Wellgo cheap stock ones - 475g
Total bike: 13.8kg (18sp)

I would like a light XC bike but I don't know whether 650b or 29er would be too expensive / handle badly / be too heavy for it to be worth it or whether keeping the bike and modifying it would be an option for me. The reason why I haven't asked any LBS is because I don't have that much money pay for their parts. Can anybody suggest any models or brands for me to look at when shopping for new parts? Or simply just some advice for how to get me out of this mess...

Here's a picture of it to give you an idea (sorry about the picture - cracked lens on my phone.)

Thanks

cooldad

Your budget is?

kajjal

Work out your budget and try a few test rides. The wheel size us only one thing to consider when choosing a bike but bigger wheels are smoother on an XC hardtail.

MTB noob

Cooldad - My budget is very varied. I have £400 cash in hand + whatever I can salvage/sell for the bike. So I'm thinking 500-700 mark depending on what the market is like right now...

Kajjal - I'll see when the next demo day is with my LBS and see what each wheel size has to offer.