The v-strom 650 makes a fairly good commuter you know
I owned a Deauville 700 for a short while and they are more top heavy that the 650 strom, less power but a little more torque.
The shaft drive is great - 16k change the shaft oil- just make sure the hub to wheel splines have been greased every tyre change.
They are a PITA to work on as everything is behind the plastic, water pump housing tend to corrode and leak or crack if hit by stones.
A very comfy bike, very roomy for pillion and you may find someone selling a bike may be selling the larger pannier lids to make the panniers larger/wider.
Bomb proof engines - I wouldn't be put off on a higher mileage one if it's been looked after.
I also had a '96 XJ600n which was the naked version of the Diversion. a good solid bike, 50-60mpg on mixed riding. crap airbox/breather pipe design pipes fill up with emulsified oil and then dumps the lot into the airbox. rear shocks are a weak point, but simple to replace.
suffers from shit-brake syndrome, but it's small light and not very fast so they are adequate enough. If I'd have known I'd be working back in Swansea I wouldn't have sold it.
I bought it for £500 in a fairly tidy state, tyres with 100 miles on them- bought a new battery, chain and sprockets, bodged some exhaust gaskets and gave it a wash - clean pass on the MOT- sold it 4 years later with a bit more corrosion for £750 to some flat earther from Neath.
The Picture below - hadn't been washed in a year - was the one and only time I took the Xj600n for a pleasure ride in the 25kI had it.
SV650 and the old CB500's and CB600's Bandit 600, ER5 or ER6 are also good options.
I'd generally avoid larger capacity bikes as you'll just be paying out for the cc's over and over again.
Larger engine = more fuel burnt, more oil every change, coolant to change - a few of the older 500cc machine were oil c-o-o-led!
Then there is the weight - I'm not saying it in a heavy to push around way, that a separate and far more personal reason to not have a larger, heavier bike for commuting.
Weight does mean better road holding if your doing mega miles on motorways and full on tourers generally are the more ergonomic to sitting there for hours on end, But the outright weight mean more power to move you along, more traction required = larger wider tyres that generally cost more when they need changing and all that extra power means you're likely changing them more frequently.
Then we come to chains - the Diversion used to cost me around £60 for a JT chain and sprockets kit, I neglected the cleaning, but lube regularly and just changed it every spring around 10k mile intervals - a chain and sprocket for an FJR is likely to be around £130 for the chain alone.
Using a bike as a daily ride is also far simpler when the bike if physically smaller and lighter - you can filter through the traffic easier, bump up curbs and park in areas where a larger bike is unwieldy and risky possibly. - Outside my work, I often have difficulty parking my Varadero, but the blokes with a 650 Ninja and 125 Duke have no such issues.
I also look at the possibility of theft, if it's old, crap and generally dirty thieves will be less likely to steal it when you leave it unneatened for hours every day - thieves do tend to scope out where they are looking to steal from and the same bike parked in the same place each day shows they can pick their time to steal it.