A Garmin, a fancy Garmin, a s/h power system or what?

hi, and thanks in advance for your patience 
Im a keen middling sort of rider in many ways
I ride with a bunch of regulars and although not the fastest Im certainly not the slowest
I have just returned from watching the Tour and comfortably rode to the top of Tourmalet via another Col to get there
Whilst abroad I have been talked into next years Etape
To be honest I was kicking myself for missing this years
In the meantime I have 500 pounds to spend on making myself faster
Mainly to get closer to the mate I rode with in the Pyrenees who is on an althoether different level
I have a nice bike with an Ultegra groupset Im happy with and nice wheels Im not even thinking of upgrading
The money will be spent on something else, thoughts as follows:
Garmin 500 - although apart from data logging Im not sure what else this serves as I have an accurate conventional HRM/bike computer
Garmin 705 - this interests me from a training point of view, but having looked at the manuals online exactly how useful is it and what do you do with it in reality?
Power stuff - this is what my fit mate is raving about. 500 nicker is pushing it I admit but if Im patient and syphon off some of the housekeeping is a possible
Winter bike - the clever moneys here, but I do not ride thro the dark months as I hate the roads this time of the year, however I do regularly use my MTB with lights, Im not sure a winter bike would actually get me out that much
Personal trainer - again an outside option, with a young family my riding opportunites are precious and any more time on the bike tough to justify
So comments welcome
I admit its a series of questions with no answer
and Im fortunate to have good biking DNA but I do have some spare cash and spending it on bikes would make me happier
For me its the 705 vs waiting to buy some SRM cranks at a good price
Dont be shy - Im a big boy LOL

Im a keen middling sort of rider in many ways
I ride with a bunch of regulars and although not the fastest Im certainly not the slowest
I have just returned from watching the Tour and comfortably rode to the top of Tourmalet via another Col to get there
Whilst abroad I have been talked into next years Etape
To be honest I was kicking myself for missing this years
In the meantime I have 500 pounds to spend on making myself faster
Mainly to get closer to the mate I rode with in the Pyrenees who is on an althoether different level
I have a nice bike with an Ultegra groupset Im happy with and nice wheels Im not even thinking of upgrading
The money will be spent on something else, thoughts as follows:
Garmin 500 - although apart from data logging Im not sure what else this serves as I have an accurate conventional HRM/bike computer
Garmin 705 - this interests me from a training point of view, but having looked at the manuals online exactly how useful is it and what do you do with it in reality?
Power stuff - this is what my fit mate is raving about. 500 nicker is pushing it I admit but if Im patient and syphon off some of the housekeeping is a possible
Winter bike - the clever moneys here, but I do not ride thro the dark months as I hate the roads this time of the year, however I do regularly use my MTB with lights, Im not sure a winter bike would actually get me out that much
Personal trainer - again an outside option, with a young family my riding opportunites are precious and any more time on the bike tough to justify
So comments welcome
I admit its a series of questions with no answer

For me its the 705 vs waiting to buy some SRM cranks at a good price
Dont be shy - Im a big boy LOL
0
Posts
I'd go for a PowerTap, and if you can find some extra pennies, maybe a turbo for the winter. Perhaps borrow one first if you've never used one, to see if you get on with it.
I honestly can't see how a Garmin will help you get faster without power.
You can get 2nd hand Ergomo BB power meters for a similar budget, but they are a lot rarer!
However, £500 will buy you around one years quality coaching, and even without power readings, just a HRM, you will see big improvements...
EDIT:
Current examples...
Ergomo set up
Powertap Elite +
You too could have excess skin like this guy!
MTB - Trek Fuel 80
TT - Echelon
http://www.rossonwye.cyclists.co.uk/
Blackpool Clarion CC
http://blackpoolclarion.webs.com/
Blackpool Youth Cycling Association
http://www.go-ride-byca.org
:shock:
It was a joke!? :shock:
The same way every cyclist managed before the invention of powermeters...
Power measurements are a great tool to have for an athlete but you can train and improve with HR, speed, gradient etc. quite easily.