Sometime around 96 I have heard NH switched over to the Bobcat compatible quick attach. But check to be sure it is the standard SAE J2513. See links below.
http://www.tractorbynet.com/forums/...-skid-steer-quick-attach-plate-406928-foo.jpg
75291d1177387373-here-universal-attachment-mount-specification-sae_j2513.pdf
The LX 565 shares the same frame with the LS 160 and 170 and the 170's predecessors the LX 665. The only difference between the 160/565 and the 170/665 is the engine has a turbo and 10 more hp. The 160 is rated 1500 lb lift, which is the same as the 763/s150 bobcat. But it can have counter weights installed to boast this to a number not published in my manual.
The 170 s rated 1700 lb lift, not sure if the counter weights are standard on it or not. So in this respect you may be able to consider it in the 773 class. I see in the manual the SAE rates the 160 at 1750 lbs lift and the 170 at 1765 lb lift. So this will be a step up from the 753
Note the L565 is the same machine but does not have the aux hydraulics fitted, so be sure your looking at a LX if you want to run hydraulic attachments.
These machines should have the turbo motor to have enough hp for high flow, but I doubt it is fitted to the one your looking at anyway.
Of the attachment you mention the only one that could benefit from hi flow imo is the trencher, and that's if you can find a trencher that has a hyd motor sized to use the extra gpm to increase the torque at the chain as opposed to just spinning the chain faster. Putting hi flow through a standard flow attachment just over speeds the attachment.
Hi and standard flow are just "loose" terms, when looking at attachments you need to match the flow and pressure of the loader, (@ 15.5 gpm, and my guesstimated 2500 psi for the lx565) to the attachment you trying to run, to be sure the loader is in the range the manufacturer recommends for the attachment.
My 2000 model ls160 is at 2600 psi where Bobcat was using 3000 psi in 2000. Newer machines have higher relief pressures, currently 3000 to 3500 depending on manufacturer being the norm.
The same range that applies to flow (gpm) for attachments, also applies to pressure (psi) Being in the upper part of these ranges, usually has the best performance.
The broom, auger and trencher would all benefit from a higher relief pressure, which increases the torque to run the attachment. NH is not a leader here, but their pressure is within the acceptable range and will run the attachment you mention from most attachment manufacturers. While lower pressure don't make attachments perform better, they do have the benefit of being easier on pumps, motors and hoses which may result in a longer life.
Ken