The simple answer to your question is yes. If you meet all qualifications to fly either under §101 or §107, you may elect to operate under either part.
Any operation of civil small unmanned aircraft systems (sUAS) within the United States is subject to §107 by default. The three exceptions are air carrier operations1, hobby operation of model aircraft under §101, and operation under the provisions of a 333 exemption. This is spelled out in 14 CFR 107:
(a) Except as provided in paragraph (b) of this section, this part applies to the registration, airman certification, and operation of civil small unmanned aircraft systems within the United States.
(b) This part does not apply to the following:
(1) Air carrier operations;
(2) Any aircraft subject to the provisions of part 101 of this chapter; or
(3) Any operation that a remote pilot in command elects to conduct pursuant to an exemption issued under section 333 of Public Law 112-95, unless otherwise specified in the exemption.
Assuming that your aircraft and operation meets the applicability requirements of §101, you could elect to operate under that part. One reason for this is due to the fact that some of the applicability requirements for operating under §101 are elective. All of those applicability requirements are found in 14 CFR 101.1 and 101.41.
14 CFR 101.1 states, in pertinent part:
For purposes of this part, a model aircraft is an unmanned aircraft that is:
(i) Capable of sustained flight in the atmosphere;
(ii) Flown within visual line of sight of the person operating the aircraft; and
(iii) Flown for hobby or recreational purposes.
14 CFR 101.41 states:
This subpart prescribes rules governing the operation of a model
aircraft (or an aircraft being developed as a model aircraft) that
meets all of the following conditions as set forth in section 336 of
Public Law 112-95:
(a) The aircraft is flown strictly for hobby or recreational use;
(b) The aircraft is operated in accordance with a community-based set
of safety guidelines and within the programming of a nationwide
community-based organization;
(c) The aircraft is limited to not more than 55 pounds unless
otherwise certified through a design, construction, inspection, flight
test, and operational safety program administered by a community-based
organization;
(d) The aircraft is operated in a manner that does not interfere with
and gives way to any manned aircraft; and
(e) When flown within 5 miles of an airport, the operator of the
aircraft provides the airport operator and the airport air traffic
control tower (when an air traffic facility is located at the airport)
with prior notice of the operation.
You could elect to not fly the sUAS strictly for hobby or recreational use. Likewise, you could elect to not operate in accordance with a community-based set of safety guidelines or within the programming of a nationwide community-based organization. If you did so elect, you would then be subject to §107.
1 To my knowledge there are no air carriers operating or authorized to operate sUAS at this time. I could be mistaken. I understand that this provision prepares the way for a future with air carriers operating sUAS in accordance with other authorizations. Think Amazon delivering packages, etc.
Note: This answer does not address what it means for an aircraft to be flown strictly for hobby or recreational use. Nor does this answer address any requirements to be met in order to operate in accordance with a community-based set of safety guidelines or within the programming of a nationwide community-based organization. Nor does this answer address how the FAA will interpret the prohibition against endangering the NAS, such as if operating over the objections of FAA air traffic or airport operators. Nor does this answer address the operational requirements of §107.
